Recently my pH has been jumping all over the place. Mostly it jumps back upwards after I have pH downed it to the 5.8 area. Within 12 hours it has jumped back up to around 6.5 to 6.7 range. Here is some relevant info. I am running a BB DWC. My tap water pH is at 7.2 without adding anything to it. I filled the res. with that water and pH downed it to 5.8 and since I was dealing with young seedlings just in Veg I ran them on that without nutes for about 1 week. About 1 week ago I added the first batch of nutes, only about 10ml of nutes for the total 18 litre res. 4 litres is about 1 gallon so the res is about 4.5 gallon res. Since the water doesnt go all the way to the top lets call it a 4 gallon or 16 litre res. So the 10 ml of nutes is relatively minor. After I added the nutes the pH went up to 6.2 and the EC reading was about 1050 microseimens which is a TDS of a bit over 500 ppm. Since that point in time the plant growth has slowed considerably, I am getting intraveinous chlorosis (veins stay green rest of leaf starts yellowing) and the pH is constantly jumping up to 6.5 within 12 hours of pH downing it to 5.8. The chlorosis I think is a sign of a calcium deficiency (possibly a magnesium deficiency). That makes total sense b/c with the pH constantly jumping so high the plant should be in pH lockout. If it's in pH lockout then the plant isn't processing the nitrogen correctly and this is leading to the calcium deficiency. To make it even worse I am pretty sure there is a small amount of algae growing in the res. I put my finger in the res water and it felt very slimey. It's not a visible amount of algae, the roots look totally fine, so I think it is a rather small growth of algae but I do think it's algae. What should I do?? Would a small algae growth cause the pH to constantly jump up so quickly thus creating the PH lockout?? My entire bucket is coverd in aluminum tape so I can't think of how to make it anymore lightproof. Basically I have decided that I should completely flush the res. Scrub the res clean. Fill it with tap water pH balanced to 5.8. Check for light leaks. Let the plant go on that for about a week and then start with a low dose of nutes again. Please give me advice and opinions fellow GC'ers.
Algae, white slime, white snot, pythium, will cause your PH to shoot up fast, best to get that stuff in check fast, treat your system with physan 20 to kill it all off, dump res, flush agian, then reflll res and start fresh. that stuff is a bitch to get rid of.