RDWC feeding topping off between res change?

[Darknes01]

Hi all,
got a question for all the RDWC experts here.
Say my ppm was 990 on the 28th and today its at 910 , should i add back nuts or when do you add back nuts?
my res has auto top off so water level is consistent and ph is spot on 5.8 all the time. I do a res change every 7 to 10 days so was wondering, do i just let the ppm keep dropping till next water change? or top it off to some point? and if so what point? back to 990? or higher lower?
just trying to understand what is the logic used when topping off with nuts between res changes and how to make sure i feed them enough but not too much.
thank u all in advance.

 

[fragileassassin]

I top off with nutes at the same strength. The stuff I use holds well so I try to mix a weeks worth of top off up in my barrel. I do my best to keep the top off barrel exactly the same strength as the system.
If you auto top off with fresh water, you wont be able to see if your ppm is going up or down, itll always go down unless they stop drinking.
Your ppm can tell you a lot of what's going on before the plants start showing its needs.

 

[Darknes01]

I top off with nutes at the same strength. The stuff I use holds well so I try to mix a weeks worth of top off up in my barrel. I do my best to keep the top off barrel exactly the same strength as the system.
If you auto top off with fresh water, you wont be able to see if your ppm is going up or down, itll always go down unless they stop drinking.
Your ppm can tell you a lot of what's going on before the plants start showing its needs.

I dont know if i agree with that honestly. Here is my logic, say i started off with 10 gallons of water @1000ppm. now say they only drank 1 gallon and did not eat at all and my auto top off added a gallon back then ppm should in theory be @1000 give or take a small amount. I dont think plants can remove the water only and would take up some nuts when only wanting to drink then my issue would be over feeding not underfeeding, but since my current situation is as follows. 30 gallon total ppm was 990, 2 days later its 910 , so even if they only drank water and did not eat then ppm should not have dropped. am i missing something?

 

[fragileassassin]

The reason we watch ppm changes is because in an ideal situation, the plants drink the nutrient solution at full strength and being happy with it. Your water level will drop and your ppm will remain about the same. If you are under feeding, the plants pull nutrients out of the water faster than they drink it and that makes your ppm drop. If you overfeed, they will drink more and uptake less nutrients from the water which makes your ppm rise.

The method you use is not wrong and people do it like that, but you wont be able to "read" the ppm as well because you're constantly diluting your nutrient solution with fresh water. Unless you're metering your fresh water that's going in, you cant tell for sure if the ppm drop is from dilution or if your plants are hungry. If you have a container of fresh water topping it off so that you can gauge how much has been replaced, you can do the math and know why its dropped. I didnt like doing this on the scale of my flower system.
In the end, most people do what works for them or whatever way they feel is easiest and you should do the same.

I put a fresh water top off float valve in my veg system. When I notice the res getting low I turn it on and let it top off while I'm doing other stuff, then bring it back to desired ppm when its full. This system is only around 30 gallons and a few inches of up and down water level never seemed to bother them any.
In the flower system I've done fresh water top off both constant from the filter and from a holding barrel and the full strength top off is what I felt was easiest for me and my system. After transplant, I leave it alone for a week or two to gauge how much they're drinking and then mix up that much in my barrel. Once things get going I do most of the work in the barrel. When its empty, my meter tells me exactly how I should mix the next batch.

Sorry for the long winded post, but I just wanted to try to say theres more than one way to do it and as long as you can keep your plants happy, that's all that really matters.

 

[Darknes01]

The reason we watch ppm changes is because in an ideal situation, the plants drink the nutrient solution at full strength and being happy with it. Your water level will drop and your ppm will remain about the same. If you are under feeding, the plants pull nutrients out of the water faster than they drink it and that makes your ppm drop. If you overfeed, they will drink more and uptake less nutrients from the water which makes your ppm rise.

The method you use is not wrong and people do it like that, but you wont be able to "read" the ppm as well because you're constantly diluting your nutrient solution with fresh water. Unless you're metering your fresh water that's going in, you cant tell for sure if the ppm drop is from dilution or if your plants are hungry. If you have a container of fresh water topping it off so that you can gauge how much has been replaced, you can do the math and know why its dropped. I didnt like doing this on the scale of my flower system.
In the end, most people do what works for them or whatever way they feel is easiest and you should do the same.

I put a fresh water top off float valve in my veg system. When I notice the res getting low I turn it on and let it top off while I'm doing other stuff, then bring it back to desired ppm when its full. This system is only around 30 gallons and a few inches of up and down water level never seemed to bother them any.
In the flower system I've done fresh water top off both constant from the filter and from a holding barrel and the full strength top off is what I felt was easiest for me and my system. After transplant, I leave it alone for a week or two to gauge how much they're drinking and then mix up that much in my barrel. Once things get going I do most of the work in the barrel. When its empty, my meter tells me exactly how I should mix the next batch.

Sorry for the long winded post, but I just wanted to try to say theres more than one way to do it and as long as you can keep your plants happy, that's all that really matters.

Excellent point. What i did a bit ago is turn off my auto top off to see by the end of day if my ppm goes up or down. aka if water level drops and ppm stays stable then my ppm level is what they are liking , if ppm goes up water level drops then i have over feed them and so on. You are absolutely correct, everyone at some point finds their happy spot.
Only reason i made this post was to find out if i should be topping off with nuts, daily , every few days or just wait to do a water change with new nuts IF and only IF my ppm is dropping( which it has been).

 

[iivan740]

I use an auto top off and I made a spreadsheet calculator that tells me how much of each Nutrient to add back if want to raise the PPM back up between res changes, which I generally do if the girls are eating a lot and/or mid week as needed. I don't worry with a 50 ppm but 100ppm drop or more and I start adding back nutrients.
My basic thought is; yes add back nutrients if the girls are eating.
The same goes for my water top off, it's the reason I auto top off the water. I want my system water full up at all times, I can check my top off tank to see how much the girls are drinking.

 

[fragileassassin]

oh my I did it again! well hopefully itll be a good convo for someone to read over lmao.

if youre dropping 80ppm in 2-3 days and its not because youre diluting it, they are hungrier. I bump mine up about 100 from the starting point when the drop is noticed for one that big.
How often will depend on your plants and how you want to manage them. I let the veg system drop around 2" before I add water. That leaves enough water to keep a vast majority of the root ball submerged. The sprayers in the flower system work better if I dont let it drop much, plus the root balls are so big large portions of them are out of water if I dont keep it up.
You can top off daily or every few as needed. just try to keep them in a fairly small ppm range and not up and down constantly.

 

[Darknes01]

I use an auto top off and I made a spreadsheet calculator that tells me how much of each Nutrient to add back if want to raise the PPM back up between res changes, which I generally do if the girls are eating a lot and/or mid week as needed. I don't worry with a 50 ppm but 100ppm drop or more and I start adding back nutrients.
My basic thought is; yes add back nutrients if the girls are eating.
The same goes for my water top off, it's the reason I auto top off the water. I want my system water full up at all times, I can check my top off tank to see how much the girls are drinking.

would u be willing to share your spreadsheet or is it custom to your setup?
thx

 

[iivan740]

yea no problem, Here's a dropbox link https://www.dropbox.com/s/6vs35u9g3h8hgsw/RDWC add back update.xlsx?dl=0 if you want to check it out, there are no macros and only very simple formulas. i would recommend you download it (to preserve the protection) and play around with it you should be able to, or you could open it in google docs and online excel. The sheet is super simple, I put my system gallons in at the top left, then the weeks initial PPM for the week in the blue box, then when I want to add back nutrients I put the current PPM in "todays PPM" the gray box. The sheet calculates the ppm drop from the last res change and suggests the ML of each nutrient to be added back.

 

[Darknes01]

yea no problem, Here's a dropbox link https://www.dropbox.com/s/6vs35u9g3h8hgsw/RDWC add back update.xlsx?dl=0 if you want to check it out, there are no macros and only very simple formulas. i would recommend you download it (to preserve the protection) and play around with it you should be able to, or you could open it in google docs and online excel. The sheet is super simple, I put my system gallons in at the top left, then the weeks initial PPM for the week in the blue box, then when I want to add back nutrients I put the current PPM in "todays PPM" the gray box. The sheet calculates the ppm drop from the last res change and suggests the ML of each nutrient to be added back.

thank u very much, this will be very helpful since this is my 1st time growing

 

[iivan740]

No problem, it's built for UC nutrients, but if you dissect it you should have good idea how to build a sheet that works for your needs. There are some hidden columns so you will need to un-protect it and unhide them.

 

[iivan740]

oh my I did it again! well hopefully itll be a good convo for someone to read over lmao. To start let me say that I was checking out your system the other day on here, It's obvious to me that you know your stuff just by seeing your journals.

I love a good discussion/debate, I would not even respond to an idiot (they aren't worth the effort). FWIW I see your points and agree mostly.

if youre dropping 80ppm in 2-3 days and its not because youre diluting it, they are hungrier. I bump mine up about 100 from the starting point when the drop is noticed for one that big.

A lot of what i'm about to spew here is strain dependent just a heads up. The systems are Relatively small 12 pot systems.

So I use to run botanicare and may go back to it. I cut my teeth on botanicare and a live system. When I ran botanicare "bloom" ppm was commonly between 1500 and 1900 on the 700 scale. Even at those high PPMs the plants would easily eat 100 ppm a day and consume 2.5 to 5 gallons per 24 hours.
Now i'm trying UC because I want to run a sterile system. I am doing this mainly because I am curious and because system water temps can be difficult for me to control sometimes, but also because I want to try out the nutrient line. My system is running the recommended PPM for the week which I feel is super low but the plants are lovin it so who knows . The system is drinking about 2 gallons in 24HR and the PPM is dropping +- 50 in 24HR.
To put this in context two weeks ago they were in botanicare at 1300 PPM drinking 2.5-3 gallons in 24HR and the new growth was turning yellow I.E. not enough nutrients. Daily PPM uptake was just over 100 in 24HR.
I guess what i'm saying here is that if I let the system go without topping off the nutrients through out the week the plants would eat over half the PPM by week end. My opinion is that the nutrients need to be topped off / kept at or close to starting PPM thfough out the week.

To be quite frank if my babies aren't eating and drinking I start to worry and troubleshoot the system.

How often will depend on your plants and how you want to manage them. I let the veg system drop around 2" before I add water. That leaves enough water to keep a vast majority of the root ball submerged.

100 yep yes sir. I vary my water level based on many factors. Mainly root development.

The sprayers in the flower system work better if I dont let it drop much, plus the root balls are so big large portions of them are out of water if I dont keep it up.

LOL Mine is rdwc in bloom and dwc with spray bars in veg (from your journals it looks like you do also). the systems with spray bars definitely do not need water micro management and they stretch / grow roots like crazy. I mean super impressive root growth even for hydro. In bloom i'm old school and I pore the air to the buckets, think mini water volcanoes of air.

You can top off daily or every few as needed. just try to keep them in a fairly small ppm range and not up and down constantly.

same page all day long, I just really like to automation and not having to top off water all the time.

 

[fragileassassin]

Thanks! Ive always been huge on attention to detail so honestly this has come pretty easy for me. I keep waiting for something to go terribly wrong and so far the worst thats happened is ive spent too much time and energy cloning a plant that turned out to be a male when I went to slower the clones lol. (im 80% sure I just did it again if im being honest, ill know for sure in a couple more days LMAO!)
I try to share my experience so people can take from that what they want. What do you tend to grow? Mine are always heavy indica strains.
Ive been using megacrop and their bud explosion and so far topped out at 1400ppm and I rarely see swings over 50ppm in 24 hours, those are my "higher nutes now" situations. Usually Ill watch it gradually drop 60-80 over 4-5 days then bump it up around 1.5x what it dropped. Sounds like I do bigger adjustments over starting point maybe? Its not uncommon for my system to stay rock solid and not sway ppm or ph at all over a week,
I have sprayers in both systems and around 30 lpm of air to each site for the flower system. In the flower system the sprayers are at a 45 degree angle and aimed to hit specific spots in the totes that I found got the best agitation of the water. If it drops more than 1/2" this effect is significantly reduced pretty quickly passed that, so i just keep it level. I grew an 8 plant 10x10 jungle last winter and at one point they were drinking a full 55 gallon barrel in 4-5 days, it was nuts. Having to deal with that really helped me figure out how I wanted to run things. Now I can walk down the stairs, see the meter, and open the barrel lid and have a solid idea of whats going on. Last thing I need to do is dial in a more specific nutrient mix for flower and im happy.
I also push the envelope with water changes. If things are going well ill go 3-4 weeks in veg and every other week or 100% system volume replaced in flower.