I did 2.7 lbs off 440w of Vero 29 SE CoB LEDs. This was only three plants though and the stalk coming out of the bucket was about three inches across. A lot of people are pushing grams per watt and mass yields, but you have to pick a good strain for it first. Some strains just don't create large yields. What strain are you using?
I F.I.M. instead of top because it can split one stalk off into 4-6 mains. So top it once at the third set of branches, then F.I.M. it when those get large enough. I start with some low stress pinch and rolling on the stems low to the bucket. It not only helps with spreading the canopy out, but it helps strengthen the branches. Once you get them huge they can get top heavy and get a gangster lean on you. If you strengthen and thicken the branches, they will hold better. SCROG it or you will have trees hitting your rafters. I used 5g buckets at the time, but I have since upped them to 12g totes in an RDWC and I expect to get better results. I have tried MegaCrop, GH Flora Series, Nectar for the Gods, Remo, and Technaflora. I had the best results with MegaCrop and Remo. I like NftG, but it tends to cause hygiene issues in DWC since it's mostly organic. I run my PH a little high at 5.9, but I find I run in to fewer lockout issues in DWC. Might just be my water impacting it though. I don't use RO, I use straight TAP that is nuted and then PHed. Mammoth P hasn't really shown to be a huge benefit, but I do use it early on still. I do two defoliations, one about a two weeks before flip to flower and one about 21 days in to flowering. This is just what works for me, but you will likely find that your RH and PH will give you different results at slightly different numbers.
I heard straight tap water makes mammoth P pretty much useless. One guy said he only started seeing the benefits of it when he switched off tap, fwiw.
That being said, I am a home grower for just personal use right now. So it does nothing for me to grow that much at once. This run I am going for more variety and quality than quantity. Instead of focusing on THC or quantity, I am trying to find the best tasting flower I can. I use a volcano, so flavor is heightened and I want to find a really citrusy flavored one.
