Nitrite spike after adding CO2

[Cococalm]

Hello all.

My established but redone 130 lit had a massive nitrite spike last night. Since installing my new Trigon 190 and transferring all my fish and inverts to this tank, I decided to redo the 130 lit. Redo = replant and change the decor ... added driftwood.

To do this I emptied the tank 50%. I vacuumed the gravel and reactivated the UG filter which had remained inactive for the last 2 years. I cleaned and boiled the driftwood before putting in the tank as I wanted to tie some Anubias to them. This occurred mid April. Other than a few (pest snails) there is no population in the tank. I reduced the tank plant population by 3 Echinodorus only and an Amazon Sword. I added equal amounts of Anubias before refilling the tank.

The tank is well planted with Anubias mainly but there are a few Echinodorus, a small Java Fern, an Apongeton and a few grass plants.

I did not have any CO2 as I had run out of the refills for the Söchting Carbonator bell I have. Yesterday I added the refill I bought and this morning I have a milky tank.

I instructed my wife to do a water change which she did dilligently .... 100%. I got home just after lunch and the water was milky again so proceeded to do another 100% water change. Unlike my wife, I added JBL Biotopol and EasyStart by EasyLife.

I want to know why I got this spike after adding the CO2 to a tank that has been running fine without it for more than a month after the redecoration. This has made me fearful to add CO2 to the Trigon when it arrives out of fear I get a spike in a populated tank ..... I simply cannot afford such a drama.

Any help would be appreciated and even any guidance on how to add the CO2 to the running "established" new tank without thee risk of a spike.

Thanks

 

[Mebbid]

My guess would be that the CO2 caused a drop in pH. At low pH (6.5ish) levels the nitrifying bacteria slows down considerably. This would cause an increase in ammonia or nitrites and an accompanying algae bloom.

What's the pH and DKH of the tank?

 

[Cococalm]

Hello and thank you for your reply.

This weekend I did the customary water top-up/change. In this case, just a top-up was required because values were good and the top-up was with rain water only. I did not do a change because of the fact that there is population. However, the top up was less than 15 litres.

Here is the values just before the top-up .... 35 minutes before. I have not taken the values now as it is not turning long enough yet and my water is extremely hard ..... GH > 21°d. I am waiting for the water to clear before adding rain water.

I hope this helps