NEW NFT (nutrient film technique) SOG SETUP

ive been doing a lot of thinking the past couple weeks, and ive come up with something awesome i think..

originally i was going to build a custom NFT gutter system, and have the gutters go back and forth, lower and lower each pass, long 8 foot guys...

but the drawback was the hights of lights and plants would varry gutter to gutter.

So long story short... ive come up with a solution that is perhaps better than the gutter system.

I will be building this in the next month, but i figure ill put it up here just incase someone has an inovative idea to add before i start construction.

This thread will show in detail how i make it, and how it works out.



HERE IS THE CONCEPT-

Instead of lots of narrow gutters... make one extremely wide (4 ft) gutter, and make it about 8 ft long.

To do this, i will be using an 8x4 flat surface, and building up 4-6 inch walls around it.

It will be water tight, and have a drain on the low side.

It will be sloped long ways... the 8ft length will have the tilt.

Then a top plane will be added that is also 4x8, and this top plane will have pre cut holes for the net pots (whatever you call them... the ones with holes all over) These basket pots will be held by the top plane because the holes will allow them to fit in, but not fall all the way through.

Panda wrap will be placed over the entire top plane to keep light out of non occupied holes, white side up. X's will be cut in the panda wrap to allow the placing of the basket pots into the holes in the top plane.

The water will run from high side to the low side of the bottom plane, and thus allow for NFT to occur as plant roots grow down out of the pots and touch the bottom plane and water flowing over it.

The bottom plane will have a wood frame, kind of like box springs to a matress... that will support the bottom plane.

I plan on using 8 ft 2x4's as the "box springs" that come in direct contact with the under side of the bottom plane.

Then 4 ft 2x4's perpendicular... under the 8 ft 2x4s, to join them all together and make a ridig frame.

There will be a resevoir, and a strong pump.

The pump will pump up to a 1" pvc pipe that goes between the top and bottm plane... at the high side of the tilt.

This pvc pipe will obviously be about 4ft long and go across the full width of the gutter.

This pvc pipe will have small holes drilled in it, down its entire length, about 4 inches appart from eachother.

The fluid will pour out of these holes evenly, across the full 4 ft width, onto the bottom plane, like a drinking fountain.

The bottom plane will have vertical walls built around the perimeter that are 4-6 inches high (depending on how deep the basket pots being used sit below the top plane.

The top plane sits on top of these vertical perimeter walls.

Glue or screws can be used to mount the walls to the bottom plane's perimeter, and ultimately EVERY SEAM will be caulked with a silicone tube gun.

At the bottom of the tilt, there will be a drain or drains that lead to drainage hoses back to the main resevoir.

These drains will have some sort of a protective screen built prior to the drain holes, so that roots and other debris CANT ENTER THE RESEVOIR via the drainage tube(s). (keep them away from the pump!)

A trap door will be put in the top plane (or simply a hole that is covered with panda wrap) which allows access to the screens for debris removal and cleaning.

I plan on this 4x8 being able to hold upwards of 150 plants IF one choses to cut the holes in the top plane VERY close to eachother.

The top plane will be held up throughout the middle of the structure by support beams sitting upright from the bottom plane, which in turn sits on the wooden "box spring" frame.

I plan on using equally cut lengths of 1 inch diameter pvc pipe as support beams for the top plane to hold it up throughout the middle of the structure, and siliconing them into place on the bottom plane... but not bonding them to the top plane so that the top plane can be removed like a lid, when no plants are present... for cleaning, maintinance to the bottom plane, etc.


The support beams are necessary because the top plane is what holds the weight of the pots and plants, suspending them an inch or so above the bottom plane so that the roots can grow down and feed off the nutrient film water flowing by, as it flows down the incline.

I also plan on putting in some sort of runners, or thin strips that sit about 1/4 of an inch up... and putting them down the 8ft length of the bottom plane, spaced about 4 inches appart. I plan on using weather stripping (unless i find something better) and theses strips will be like LANES for the water.

Otherwise, i feel that the water would all bond together in a single, narrow path, by the bottom of the 8 ft plane, and MISS CERTAIN PLANTS... if that makes sense?

The lanes keep the water spread evenly across the full width (4ft) of the bottom plane, so that all plants above have an equal shot at taking a drink.



Materials:

After wandering around lowes for about an hour, i figured out i want to use the 4 ft, 1 inch diameter pvc pipe with holes dilled every 4 inches down its entire length, corrosponding with the lanes. This pvc pipe will be labled as the "fountain" at the top of the incline.

A hole will be cut in one of the perimeter walls, or the top plane, to allow for the hose to enter the 8ft x 4ft x 6inch box. This hose feeds the main fountain and is attached to the pump in the resevoir.

The material for the planes was the hardest part, but then i found the perfect stuff. There is pvc WALL PANEL that is typically used for bathroom walls. This stuff is rough and course on one side, and prefectly smooth on the other.

I HAVE NOT YET DECIDED IF THE BOTTOM PLANE SHOULD USE THE SMOOTH SIDE UP, OR THE ROUGH SIDE UP... i think both have their advantages... as the rough side will keep the water churning, and perhaps more oxygen, as well as keep the water from accellerating as it goes down the 8 ft length.

I have not decided yet on the material for the perimeter walls, if it be wood 2x4's wrapped in waterproof tape, and then siliconed into the top of the bottom plane, or if i should use metal L or C beams? or any other ideas???

I will use weather strip spaced about 4 inches apart all the way down the length of the top of the bottom plane, to keep the water lanes, and water evenly divided across the 4 ft width of the incline bottom plane.

I will use fiberglass screen (like the stuff used in your windows to keep the bugs out) to guard the drain holes at the bottom of the incline that drain back to the resevoir.

I will use plastic fittings at the drain site to attach to rubber hoses that gravity feed back to the resevoir. I will use these fittings also to attach the FOUNTAIN 4 ft pvc pipe, to the rubber hose that it fed by the pump in the resevoir.

I plan on cutting equal sized holes all across the top plane, to allow for the pot baskets to fit down in and suspend from the top pvc panel plane... which is held up by the perimeter walls, and the pvc support beams through-out the middle between the top and bottom planes.

I plan on using silicone to seal every seam, and make the bottom plane and the walls all water tight. The top plane will lift on and off like a lid. I might cut the top plane into sections to allow for some plants to remain in place while other sections of the top are lifted off for cleaning.

I plan on putting a trap door or hole covered by panda wrap, down by the screen which protects the drain, so that debris can be removed without lifting off the top plane.


The holes cut in the top plane will be spaced close together at the top of the incline, and then one could space them farther appart towards the bottom. This allows a person to grow the plants, and move them down to spots where the plants have more space away from one another as they progress, like an assembly line.

If the plants are pruned in SOG method, and kept thin, then i see no reason why this couldnt hold upwards of 150 plants for 4x8 ft area if small enough pot baskets are used, and small enough holes are cut in the top plane and put close together.

I plan on building 2 of these boxes, one for MH lights, and one for the HPS bloom lights.

In a 9x9 area, 2 of these "boxes" could be placed easily, and a panda curtain could be used to keep light cycles seperate.

I plan on the top of the box to be about 2 ft off the floor, and the bottom plane to be about 1.5 ft off the floor, and the resevoir to fit under that, like a large wide short rubbermaid container.

Hopefully i did a good job describing what i plan on doing. I plan on just building one initially, and maybe just switching out lights to hps, and seeing how the plants do... or building a second one in time for once the plants get ready for bloom phase, and just move them over.

The baskets should be able to pull in and out with ease.

The panda wrap on the top planes job will be to keep ALL LIGHT OUT of the box to avoid algea bloom.


ADVANTAGES I SEE TO THIS SETUP OVER OTHERS...

1. one resevoir, and pump is protected by screens by the drain.
2. Holds as many plants as you want it to... multiple top pvc panels could be used, so you could switch just the top if you wanted to grow bushier or thinner plants.
3. MINIMAL GROW MEDIUM WASTE. The basket pots are recyclable, and simple loose rockwool could be used, or even stones that have a larger diameter than the pot baskets holes.
4. EVEN DISPURSEMENT OF NUTES TO ALL PLANTS VIA THE LANES.
5. ROOTS CAN GROW INFINITE LENGTHS, AND THUS PLANTS CAN ABSORB MORE NUTES, AND THUS GROW LARGER THAN IN ANY OTHER MEDIUM.
6. ONE SHOULD BE ABLE TO PURCHASE ALL PARTS NEEDED FOR BUILD FOR AROUND 200 DOLLARS... (with the exception of the pot baskets, panda wrap and pump) very cheap!
7. Foggers or sprayers could ALSO be added within the box! 4 Bowl like resevoir holes could be cut in the bottom plane, and a bowl siliconed into place, and a fogger placed in that recessed bowl, which would in turn fill with water, and stay full at all times... (pump stays on at all times, so water would always be flowing by, keeping the recesses full) This could fill the entire 8x4 ft box with fog, aiding in evern more nute absorbtion. Sprayers could be used, but this would require additional plumbing.... but either foggers or sprayers could be added at any time, as well as drip water systems into the top of the pot baskets.... but i think this would be overkill personally.

If you dont understand the setup... give me some time, and once i start building i will put up some pics and let you know how it goes!

Please throw out any other additional ideas that might help me with my build. Thanks guys!!

Wow ... alot of typing and no photos...

I think your doing alot of work and money when you could just buy a system and save yourself alot of time and hassle and possibly money and room lol when a cheaper system could produce the same yeilds along with if you ever move wtf do you plan to do to get it out? It sounds huge and youd have to destroy it getting it moved... unless u kno how to build it so u can break it down...

dripdrew said:

I think your doing alot of work and money when you could just buy a system and save yourself alot of time and hassle and possibly money and room lol when a cheaper system could produce the same yeilds along with if you ever move wtf do you plan to do to get it out? It sounds huge and youd have to destroy it getting it moved... unless u kno how to build it so u can break it down...

Click to expand...

yeah... ive decided im going to build a 4x4 box first... for the size reasons you mention.. and just to test the setup... but if it works as i hope, then an 8x4 will be coming soon after.

they sell 4x8 plastic latice at lowes, and i found that the pots fit perfect in the holes. I will use that at the top plane.

as far as holding as many plants as other systems... the 4x8 latice from lowes has 233 holes in it...

you show me a sog technique that allows for 233 plants in a 4x8 ft area... and costs 200 bucks, and ill buy it!

sherriberry said:

yeah... ive decided im going to build a 4x4 box first... for the size reasons you mention.. and just to test the setup... but if it works as i hope, then an 8x4 will be coming soon after.

they sell 4x8 plastic latice at lowes, and i found that the pots fit perfect in the holes. I will use that at the top plane.

as far as holding as many plants as other systems... the 4x8 latice from lowes has 233 holes in it...

you show me a sog technique that allows for 233 plants in a 4x8 ft area... and costs 200 bucks, and ill buy it!

Click to expand...

223 plants in a 4x8, now I know your green behind the ears. A lot of reading and no growing experience.

Good luck getting that many plants in that space, two plants vegged properly will fill that space better and give you more buds than a mini SoG. Since you also sound like your new to the hobby, not saying you haven't done your reading, because it seems you have and that is good you should maybe start and try and veg a plant as big as you can and fill the lattice with that. I suggest using nylon netting. It will block less light.

Start small and grow.

Get you some CFLs (Daylight 6500k) and some coco coir and perlite and some seedling starting trays. Start off a small box, grow a mom. Make clones. Veg your clones for a month and sex them. Kill male flowers, there will be some. Fill your 4x4 with 9-12 month vegged clones under a 600W - 1000W digital. This is the best recipe for success with an 8x4 area, I would use 4x4 for a tent for flowering and the other 4x4 area for clones and mothers, maybe get a MH for that area. If you got the space go for it.

Flowering style will be your choice at that point. You can lollipop, ScrOG, or let it grow all natural.

~GG420

are my 2 sunblaze, 4ft x 2ft, 8 bulb, ho t5's enough?

or how about my 2 cool suns, one with 1000 watt hps, and the other with a 1000 watt MH sunmaster cool delux enough?

as far as the 233 goes, i understand EVENTUALLY the plants will out grow that format.... however... as i said earlier... i plan on building more of these as the plants need more space.

233 plants can, and will fit as long as they are young enough, there is over a 1 inch gap between each 3" diameter pot.

Can i have 233 small plants simultaneously? Id need a lot of clone boxes, agreed...


But my point was... that lattice is a great solution because it already has the holes... so no cutting needed, and it can hold UP TO 233 in a 4x8.

My biggest concern right now is keeping light out of the box, and what im going to make the perimeter walls out of.

i think in addition to the panda wrap, which will have X's cut into it at each hole site...

im going to get some sort of light proof lids from some where, and put a lid over each X if there is not a plant in that hole. The lids will just lay on top of the panda wrap, nothing fancy. Could just be squares of black plastic cut to size... who knows.

Thank you for the advice, and i do agree with you. Lets try not to make negative assumptions

empty net cups w/ a collar will fill the holes and block the light

Well my local store has a 156 site aerogarden thats about 4×4 and i plan on doing two of them for a sog grow...

Wow ... alot of typing and no photos...

Click to expand...

^^^^^^^^^^^

i bought the supplies today, i will start construction tomorrow. Ill have pics up for ya soon!

How much is the one at the store that you saw?

Also, what form of aeroponics does it use? (describe in detail if you can)

And how much is the thing?

Thanks!

i am as new to this as an infant is to life, so i have some questions and i would really appreciate if you could provide me with some answeres. How big would a room need to be to hold this type of system. Do you think led lights would be an effective form of lighting[im trying to cut down on energy cost]. If all 150 pots were accupied approximatly how much would i be looking at come harvest time.

For the bottom plane I would have used 3/4" plywood or better and used 1x6 on the sides. Use reenforced brackets on the corners and then laid a layer of pvc or epdm pond liner down to make it water tight. All of that stuff can be found at lowes or home depot
$30 for the plywood
$30 for the pond liner
$25 for the 1x6 and a couple of 1x2s for structural support
$10 for all the shit you need to keep it all together.

plywood is a good idea.

Ive already built it for the most part using 2x4s laid flat to hold the bottom pvc panel plane.

Plywood would have been easier tho for sure.

THe pond liner is a good idea.

It might be something I can still add...

however, making it perfectly flat, AND adding the strips to keep the water in lanes... might be a challange.

WHat are your thoughts?



To manwitnoface-

You could harvest in just this platform... but if you want to set up an assembly line, then youll eventually have to build a second and possibly third one of these, depending on how bushy your plants are during harvest.

Im thinking that this first one that im building will actually hold more plants than 150. Its a lot of fun, it reminds me of a pinball machine kind of... the races, and the water and the drain holes, and directing the water to the drain holes with the races... and im debating on setting up a section for fresh clones, that are still barely rooted, and putting a fogger inside this box, over in one of the corners.

Ive made my final decision on the net pots... after a lot of research, im actually going to go with 2" netpots, and neoprene collars...

after seeing stinkbud's setup, ive realized plants can harvest in these small 2" netpots.

I might cutt he bottoms of them out tho.

One can either go from rapid rooters, and put those in the net pot, or use a fogger cloner, or ez cloner, and put just the collar ont he plant, and not use any rapid rooter or rockwool at all, and let it just hang in free air in the pot.

Im thinking my 5x4 is going to hold possibly 200 plants... and for those of you wondering how im going to do thise using the latice im using, stay tuned... im wrapping the panda wrap to the latice, and cutting a hole in the panda wrap that is only big enough for the 2", and then lining that hole with tape to reinforce it around the edges so the pot doesnt fall through.

But.... i think there is some smaller lattice pattern out there... so im looking to find some for 2" pots.

At this point, the limitation will not be the table, so much as enough cloners and mothers to keep up with keeping this table full.

I went with 2x3 for the top plane support, so the top plane is 2 3/4 above the bottom plane. THis will be perfect for small plants just coming out of clone, as they will not have to grow ling roots to hit the bottom and start feeding.

The plants will need to have water and nutes hand poured on them in the begining.

as i mentioned before, im contemplating designing a sprayer setup inside the box.. in addition to the nft.

The srayer would be on a timer, 1 min on, 5 off. The nft would be constant

THis means 2 pumps are needed... not big ones tho.

If this first table is filled to capacity... AT LEAST 2 flower tables will have to be constructed to keep up with the many veg'ers coming off this table.

The plants take up more space once they are ready to flower, thats why 2 tables would be needed to keep up with this one where the plants are super close to eachother.

Let me know soon on that pond liner stuff, im interested, but not fully familiar with it.

yeah, i just figured it out...

if one used the pond liner on top of the plywood, and had some double sided THICk tape... the thickness is needed and on purpose...

if the double sided tape was laid longways, and about 3 inches appart, and a person was really careful and took their time laying in the pond liner...

the tape would create the lanes or races.

the lanes are necessary to keep the water evenly distributed across the width of the box, otherwise it will all combine.

Take it one step further... if a person put 1/4 inch pvc down on the plywood first, and set up plumbing for sprayers, and then laid the pond liner in there on top of it, and drilled the holes into the pvc and the pond liner, and had the sprayers stick up through the pond liner.... i dont know if it would leak, but if it didnt, that would be ideal because the pvc would create the lanes.

I think you might have outsmarted me big time captain insaneo

ps- panda wrap might be cheaper and just as effective as the pond liner stuff...

like i said, i dont know how thick it is or how it works, but ill go check it out at lowes tomorrow

Sup man, im also building a custom NFT,.. ive built the stinkbud system and have no doubts on the benefits of NFT
Heavy fast yield, no media to lug and wash, reduced maintenance etc..
I almost regret spending the cash on the mateirials to build the Stink set-up and
instead should of built a custom NFT system to the dimensions of my room to maximise yeild/space BUT i cant complain
cos the Stink system helped me get a handle on NFT, understanding it, getting it dialed in etc (shout out to stinkbud, great guy)
so yeh im really interested in seeing
wot you come up with cos im on
the same trip myself, ur on to a good thing so keep it up..
As for NFT SOG max yield strain have a look at this green giant x ak47 https://www.rollitup.org/grow-journals/101347-critical-mass-tree-grow-x-6.html its by spice bros
but i dont think its around anymore
Im running with MR NICE SEEDS black widow (the real white widow) and medicine man (the real white rhino)

yeah, ive got my table built... no plants in it yet tho... i think i have the setup figured out from start to finish.

It will use the stinkbud setup for flowering.

It will use the table im making for the 1500-3000 ppm veg nutes and a 1000w mh light.

it uses sprayer tubs for cloning.



The clones go the the sprayer tubs. Get about 2 or 3 of them going, holding a total of around 150 plants

I have a transition tub tho (its a gigantic tub sold at lowes that is about 3.5 ft long, and pretty tall... with about 100 holes in the top of it for the 2 inch net pots, with nutes around 600ppm)

Then, once the roots really take off, i move the plants onto the table.

The table will hold 150 plants easy, and actually more... and i only built the 4x5 ft one. There the nutes will be around 1500 im thinking.

From there, they go to the stinkbud setup for flower, because... stinkbuds system keeps the plants seperated enough anyway because by that point they are going to be getting bigger.

A table could be built, but honestly ive come to ask myself "why"? (unless you want to do a sog and are going to be lollipopping)



The best way to build a table is very simple.

Get a piece of 3/4 inch plywood.

get some pvc pipes, arrange them in long rows down the length of the plywood, one about every 8 inches. Have them all connected by one latteral pipe of much larger diameter either at the top or the bottom.

Drill the holes in the pvc pipe... install around 40-70 sprayers.

Get a 1700 gph pump off ebay for 70 bucks.

build a perimeter wall that sits on top of the plywood. Make this wall as tall as roots need accomidation for.

(if plants are small, use 2x6 wood. If plants are very large and flowering, maybe 2x10 or larger)

Instead of the lattice that im using...

one should use the pvc sheets for the roof or "lid" to the box, and just drill the 1 7/8 inch holes into that for the 2" netpots.

Also, drill 1/2 inch or 3/4 inch holes in it, and cut pvc pipe slightly longer than the hight of the 2x6 or 2x20 that you are using.

These pvc's will be support beams to hold the lid up throughout the middle of the box, and just sit on top of the panda wrap which ... ill get to.

THe reason you want to run them slightly longer than the hight of the walls is because you want them to stick up through the holes past the hight of the lid... and run a glue bead both on the top and the bottom side of the lid around the support beam to join it to the lid (otherwise its hard to keep them glued to the lid without having the hole in the lid)

The panda wrap is used as a bladder for the whole system. The panda wrap goes over the pvc piping that lays flush on top of the plywood. The pvc piping already has the holes dilled for the sprayers.

The sprayers go THROUGH the panda wrap, into the pvc pipes holes. The sprayers are the only thing that sticks up above the panda wrap. Poke holes in the panda wrap after you have it laid out nice and flat on the plywood, and it will come up and over each pvc pipe, and then back down against the plywood. I used double sided tape.

Then, poke holes in the panda wrap where you feel the pre drilled holes in the pvc pipes.

THen put the sprayers into the pipe through the panda wrap.

You could have a pre drilled hole drilled in the plywood for the drain, or try to figure out a waterfall system like stinkbuds.

The panda wrap comes up and over the side wall 2x6's... a bladder is created. The only hole is the drain hole, install a sandwich style drain sold at hydro stores that screws in and clamps from top and bottom.

obviously put legs under your plywood and give it a slight tilt.

Put the res right below the drain hole.

Get pvc pipe that slides around the drain nipple fitting in the table.

Put a lid on the res, and drill the hole in the lid for the pvc pipe... to exact size.. and the hole will actually HOLD UP the pvc pipe.

Then, the pvc pipe goes verticle up to the drain nipple on the table.

This can be slid up around the nipple, and the lid holds it in place...

WHen you want to get the res out from under the table, just slide the pvc pipe back down into the res, and away from the nipple.

This creates a light tight, leak proof, evaporation resistant system.

The lid... get the silver waterproof tape sold at lowes, and creat a little 1-2 inch flap that comes down from its bottom surface, just instide of where it sits on the wall.

This flap goes all the way around the perimeter.

It keeps it from leaking at the top.

Sprayed water wants to fly out from between the lid and the top of the walls. This flap hangs from the under side of the lid, and sits almost flush against the wall, but is not attached to the wall.... but it prevents flying liquid from hitting the crack between the lid and the wall, and the liquid just drips back down the flap... its like a weather stripping concept... but different.

2 other things... first is... you dont have to shut off your sprayers i dont think like stink does.... the water has plenty of oxygen in it because its spraying.

this then means you dont have to build the fountain head for the contstant nft... the sprayers create the nft.



Id take pictures, but my camera is busted and im tool lazy to buy another.

Soon... sorry guys.

Just FYI for your NFT, this is what I've figured to be best to make an EVEN flood across a plane:

You need to make a trough for the pump to pump water into that goes across, the plane, like a 4ft piece of rain gutter. The pump fills the gutter until it overflows and if you pump fast enough and make it level legnthwise it should produce an even stream.

It does not half to be level widthwise -- and may even be better tilted so it doesn't fill as full, and produces more of an even flow.

There are three basic things to NFT that need to be met and considered carefully in the planning stages:

1) The flow needs to be quick enough so there are no 'dead spots' or spots where the water is pooling up, but not any quicker than you can possibly make it other than that... Too fast of a flow will result in very poor nutrient uptake...

2) The nutrient streams thickness needs to be as close to a 'film' as possible, aka as thin as you can make it without disregarding the aspects of #1..

3) I don't know, everyone says 3 things, you guys start in and help out and turn it into 30!

quick extra reply:
If you use a pvc pipe or hose drill many smaller holes across it, like every 1cm or even 1/2cm apart, it may be better for creating a small film actually, and you can slant the table accordingly..remember to test this all out before mounting/screwing stuff together by making a 4x8' plane like you're planning with the pump and everything assembled, and pumping the stream down it and adjusting the tables angle... get something similar to roots to simulate root mass being there too, like loose rockwool strands or bushes of thin twine or something..

A good thing to remember is the top 1/3rd of the roots like mainly air and just a lil water, the middle likes an air/water mixture, and the bottom of the root can handle a solid water mixture best.. It works all other ways but from all the reading I've done that's pretty much the best..

So a good solution is to make a aero setup inside this and lift the pots up about twice as high as you were thinking (12-16", so the 'base' of the pot is about 8-12" from the stream) and you can use it to spray the roots while they're still forming, before they can reach the film.

If you put a lot of sprayers (you can just drill small holes into PVC pipe or into a hose btw, or you can get little push-in 180 & 360 degree sprayers to put into drilled holes) all the way around where the pots are, and put a small barrier at the end of the table where it drains off so the water level gets to a certain height (about 1/2cm to 1cm deep across the table, doesn't need a slant this way it will just fill up and drain out of the end, and since the sprayers are coming from everywhere there are no dead spots.

Also this way you can adjust where the sprayers are going and end up with semi dry upper portions of roots, sprayed on where you want it, and a film in the bottom of water for them to suck up as much as they need..

The pond liner is going to be bumpy and make uneven areas and is going to make for pooling problems, I don't know how you're going to solve this other than using a sheet of hard plastic or something like a carpet-cover for an office chair and using caulking(sp?) around the edges where the wood joins to the 2x4's..

I hope this gives you some ideas.. i'm really interested in what you end up doing so I'll be watching your thread..

Boy that ended up being 'quick'.. =P