Theory on pH swing...

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pgjz7c

Aquarium Advice Newbie
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Oct 6, 2015
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To begin this thread I'd like to give the back story. For a good period of time my 6 year old plants aquarium was getting some user old tank syndrome. I was really only doing monthly water changes and just adding water to correct for evaluation. Nothing much else.

A few months ago I got that much of motivation again and wanted to really get the plants going. First step was to identify my crazy algae perform and what the heck let's get a water test kit.

Well, whoa! Nitrite - 0 ppm, Ammonia - 0ppm, KH - 8', GH - 380ppm, Nitrate - 100ppm, pH - 6.8. So, obviously several red flags. Only adding for evaporation on the regular, rarely changing water, and rarely cleaning out my canister filter was really awful. It however never really raised alarms because fish never really died. Things looked good health wise other than way to much algae growth.

Due to this I started a frequent water change cycle of 25% several times a week. Got everything back where I need it. Nitrate still not perfect but better at 30ppm and GH at my tap water standard of 180ppm. A little later got some more flourite gravel to beefen up my substrate, picked up a couple new plants, started doing some diy CO2, and picked up some NPK seachun fertilizers.

All this was going fine. pH happily sitting around 6.8 then I had the bright idea of scraping off this very thick layer of algae I'd allowed to grow on three of the side of the tank in my campaign to help get it under control. The real thought process was if I do this my algae eating fish will eat the stuff on the plants not the walls. Now ever since this my pH has not slowly crept from 6.8 to 8.0 over a two week time period.

Currently my readings are KH - 6ppm, pH - 8.0, GH - 180, and Nitrate - 30 ppm which is stubbornly hanging on. So to get my pH under control I though I was dosing to much co2 which was converting into too many carbonates increasing my alkalinity, but why didn't my KH readings increase? So maybe nothing there.

For now I'm ceasing fertilizer and CO2 addition with bi-weekly 25% water changes until things seem to self correct. Do anyone have any advice or theories? Did doing a mass algae removal cause some sort of imbalance?
 
The algae was undoubtedly due to your high nitrates. Algae does go away overnight if it sounds as bad as you make it out to be. It can take a few weeks of work.

I'd say your pH is simply trying to normalize. Not changing water plus co2 caused it to drop and now that it has ceased plus water changes it is trying to return to normal from the tap.


Caleb
 
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