ok I have a few questions, all about the roots, directly and indirectly. First, I was wondering what ppm you're at now? I noticed on the 8th you were at 1000, 3 days before that you reported you were at 800. (Also added chlorine) It's the 17th almost 18th are you still at 1000?
Also what kind of water are you using? is it city? is it well? filtered ...etc. One thing Ive noticed is, no offense of course but it seems you may be a bit nute happy if ya know what i mean. Raising, lowering within days and looking for immediate results. Well, plants don't work that way usually. I was also curious to know if you've just ran them a 5 days to a week with just water nothing added?
And are you still using vinegar? i don't think so since it hasn't been mentioned in a while but that will have significant effects on your plants. one thing is ( I think you noticed) the pH don't stay stable very long at all. drops fast plus I believe it can have some effect on root growth. as well as the chlorine. I do know it's suggested to let tap water sit out for a couple days to let the chlorine flash off before using it on plants. That tells me chlorine = bad for the reefer. Also the air stone I have is about two inches across and about 3 inches long, looking at the amount of bubbles on the top of the water in your photos it puts out about 5 time the bubbles you have going on. those wal mart ones the blue stones, blow through it if its not easy to blow through it's garbage. your cheeks should NOT puff up if its a good stone you should be able to blow freely. also that stone i have is cheap & chinese but is a coarse stone, thus lot's o bubbles. I wouldnt think twice about using it in an 18 gal sterilite w/4 plants going at once. (actually after harvest i am! clones are already cut & starting!!) if you really want cheap tho make one or two in your case, visine bottles with many holes punched in them work very well. just have to weigh it down and the dropper one the end should be drilled out a tiny bit bigger and it fits right on the air line. we have mountains here an many rocks, I took one about the size of a tangerine and put it in my tank on the air line and that keeps it from floating. ( still using a visine bottle in a paint can that has one plant in it, the same one I had the slime probs with, recently rectified w/o chems of any kind and have new long roots...) will pry my other eye back open and read more and proof read my shit and see if I forgot anything. yo man please let me know those details though they may help a lot. ill take a pic of that stone next to a pop can for reference and try to get a pic of it in action.