Hey Al.
I have read almost all of your posts in your long threads. I have learned a great deal from you, many thanks for sharing your knowledge.
I am in the middle of expanding and changing my grow room, to try to mimic your setup.
I will be using 3 3'x4' tables under 600W HPS in BlockBuster Reflectors.
My first table is up and running and I am attempting construction around it.
I will be putting the girls in 35 5"x5"x7" square pots using Rockwool Mini-cubes. ( 1 cm)
What flood schedule would you recommend for this media? I started at 2 floods a day but they were looking a little droopy so I backed off to 1 a day.
They are 3 weeks in and about finished stretching. Everything is looking very good except for a few stunted plants that weren't strong clones to begin with.
Should I move back to 2 floods a day now or at any point in the future?
Also do you think it would be OK to use an oversized rez (30 G) and use it to flood 2 tables? Flooding about 30 mins apart.
Thanks Again
RW mini cubes behave very similarly to RW floc, which is to say that they saturate (too) easily, which drives all the oxygen out of the medium. As you know, this will damage if not destroy roots. By the time you see droopy plants, root damage has already happened. The plants will be significantly set back in development due to root system damage.
It is between difficult & impossible to recover a damaged root system in flowering plants. Once the plant is in flower, the clock's ticking. That plant's going to be finished growing & will start dying off after 8-9wks of flowering. Whatever yield you get will be closely correlated to the health of the rootmass during flowering. When you harvest poorly developed plants, there's an excellent chance you will find an underdeveloped or partially rotted rootmass, depending upon when in the flowering cycle that the overwatering occurred. If the plants have consistently been overwatered since the beginning of flowering, the entire rootmass will be sparse and underdeveloped. If the overwatering occurred later in flowering, you will find a more developed rootmass, but a significant part of the rootmass will be tan/brown (ie. dead).
Overwatering damage is one of the most common failures I see in grow ops.
It is necessary to limit watering in RW to only the amount of water that the plant & evaporation can remove at least half of in 24hrs. This is to say that you must not water again until half of the water held in the medium has been removed by the plant or evaporation. In most cases with RW, this means limiting watering to 1x/day if not 1x/2days, or even less, particularly with very small (young) plants.
I stopped using RW floc in my flowering plants simply because it holds way too much water for SoG flowering plants, which never get particularly large. Plants that don't get very large can't remove a lot of water from the medium. If your plants can't remove a lot of water from the medium, you can't water very often. If you can't water very often, you can't take advantage of introducing oxygen to the rootmass via that dissolved in the nute solution, either by an airstone or H2O2.
I've been using Fytocell media for my flower plants for some years now- works so much better than RW, though it is necessary to pack about 25mm of RW floc in the pot bottoms to keep the Fytocell granules from escaping the pot drain holes. Have also trialled some Sure-To-Grow 'Hail' cubes, which perform about as well. If you can't get either of those, try perlite with a 25mm layer of RW floc tightly packed in the pot bottoms.
I hope you're talking about using more than one 600HPS over your 3x 3x4 trays. Should be 1x 600 per 3x4 tray.
I prefer to use 4 trays & 4 separate tanks; this give me the ability to run a different nute mix in tank/tray 3, which handles plants in weeks 5-6. For week 5 in tank 3, I use Canna PK13-14 at 1ml/L & Flores at 3ml/L. At the end of wk 5, that tank is dumped and renewed with a mix containing just Flores at 4ml/L, the same as all the other tanks.
Using 1 res per tray also has the advantage of limiting the spread of any root diseases to only one batch (though with properly applied H2O2, you shouldn't have any root diseases) as well as limits the amount of damage that will be done by an individual pump or timer failure.
