Yeah green bottle is a no go for hydroponics. You will be fighting medium PH a bunch and just too much of a hassle to mess with. If I were you I would switch asap.
In this article, we are going to look specifically at the effect of the ammonium/nitrate ratio and its effect on the growth and development. Read more >
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That is a good read on understanding the drawbacks of using the green grow big bottle. Also with understanding the labels when using nutes in hydroponics and what to look for. NH4 (ammonium) is used more for soil where microbes will break it down into N03 (nitrate - plant available N). Basically the green bottle is geared for stuff like Ocean Forest or
Happy Frog. The ideal ratio of NH4 in hydroponics is 5-10% of total N. Green bottle grow big is pretty much 50/50 of that makeup in NH4.
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Water level in E&F will get a nute buildup. Depending on how long you veg its a good idea to top flush when you change the rez assuming you are changing and not doing strict add backs the whole time. Usually around once a week. Sure any of that stuff will help but isn't "needed" per say. Just use fresh nutes on a change. I would never flush with plain water till the end.
You are getting away with flooding an 8in block of coco twice a day in flower? 6in white hydro pots (1 galish) on E&F was a good 3-4 times a day during flower with the lights on on for me in coco w/o perlite. More with perlite.
Try upping the fittings to 1in and maybe running a bigger pump if need be. Same with line to the pump and outlet to the pump. E&F shines in how quick the tables drain and fill. The quicker the better. This is just a suggestion for tuning E&F more and not required if not already doing that.