Fluval stratum not lowering ph?

[Samuel Raga]

So I have set up two tanks, one 10 gal and another 5gal... I used fluval stratum in both, because the goal was to have crystal shrimp, been using RO water remineralized with salty GH, so the water comes out pretty soft, with a ph of 6.6 - 6.7 and a TDS of 130, KH 0 and no nitrates or nitrites, its RO water of course... The problem comes when I add such water to the tank, its been about a week since I havent done a water change, but the ph keeps going up to 7.8 - 8 instead of dropping to 6.6 - 6.8 like it should, because thats what fluval stratum is supposed to do right?... I have also tried using a PH liquid from seachem that drops ph and it works for like 10 minutes, but then pH goes straight up again... I have no Idea what Im doing wrong and why Ph is not coming down like it should... Again, a little more than 2 months since the tanks were set up so I dont think the substrate is already exhausted, is this normal?? Oh and the water keeps getting cloudy and it just doesnt go away after so long.

Edited October 13, 2020 by Samuel Raga

[yannachka]

what all do you have in your tank decoration wise? what is your gh and kh levels? it sounds like something in the tank is buffering the water well enough that the ph is staying high. 

[Samuel Raga]

Mmm I have 3 rocks that I dont know the name, they look kind of grey/blueish and some driftwood, and I bought these at my lfs so they are aquarium safe. One cattapa leave in there that I bough from aquarium coop and the rest are all plants... like I said, GH comes out at around 60 - 80 ppm, and KH is 0 because I remineralize RO water with salty shrimp GH+ since the tanks are supposed to be for caridina shrimp. Thats one, the other one has no decor at all, just plants and its the same thing. 

Edited October 13, 2020 by Samuel Raga