pH Dropping Drastically in Dirted Tank During Cycle. Is this Normal?
Hey guys, Iíve got some really weird stuff going on in my first dirted 10 gallon tank which is just wrapping up cycling (started 8/10). I set this thing up with ~1 inch of 50/50 miracle grow organic potting mix and worm castings capped with 1.5 inches of eco complete. Itís heavily planted and itís been cycling for approximately 5 weeks. I thought it would have cycled more quickly due to a bag of bio rings and sponge I added to the filter from a well established tank, but Iíve been having the cycle stall out due to drastically dropping pH. Near the end of the cycle, the bacteria that convert Nitrite to nitrate have been doing fine. I never record nitrite at all, but when dosing Ammonia, it can take multiple days to get from 2 ppm to 0. Iíve done full water changes (7 gallons) with remineralized RO/DI water with a TDS of 250 ppm, KH of 4, GH of 11 and pH of 8.3 When I do that, the ammonia converts no problem in under 24 hours, but the pH drops drastically in the course of 3 days and then things begin to stall out again. Are high nitrates causing this pH drop? Or is the soil dropping my pH? Could the spider wood and Indian almond leaf drop pH from 8.3 to 5.7? I doubt it. I know the aquarium cycle lowers pH, but this seems extreme.
Hereís an example:
9/12 - I do complete water change with the remineralized water mentioned above. I then add 0.3 grams of ammonium chloride bringing ammonia in tank up to ~2 ppm.
9/13 - Ammonia = 0, Nitrite = 0, Nitrate = 20, pH = 7.5, temp = 75.6; I add 0.3 grams of ammonium chloride to bring ammonia to ~2 ppm.
9/14 - Ammonia = 0, Nitrite = 0, Nitrate = 40, pH = 7.4, temp = 76.7; I add 0.3 grams of ammonium chloride to bring ammonia to ~2 ppm.
9/15 - Ammonia = 0-0.25 (closer to 0), Nitrite = 0, Nitrate = 40, pH = 5.7, temp = 73.6. I test GH and KH to compare to the remineralized water I used. GH = 11 (unchanged) KH = 1 (so test turned yellow on the first drop meaning all my KH was pretty much consumed in 3 days).
I complete total water change (7 gallons) with same 250 TDS remineralized water. After the water change, tank pH was 7.9. I add 0.2 grams of ammonium chloride. I think my cycle is complete and Iím trying to figure out how to keep my bacteria alive and at the same time keep my pH from dropping like crazy while I order and receive my Neocaridina shrimp.
9/16 - Tank pH = 7.7 (still dropping)
Please let me know what you think. This one is beyond me. I want to keep dosing Ammonia to ensure my bacteria stay alive until I can get shrimp for the tank, but this type of huge pH swing would decimate livestock. Can anyone give me any advice here? Iím out of my depth. Iím contemplating adding a media bag of aragonite to the tank to try to raise my KH even higher and buffer my pH, but I donít want to raise the GH any higher than 11 as I donít think the shrimp would thrive in that environment. Please help!