Hi everyone this is my first post on this site, I could really use some advice from more experienced fishkeepers!
I have three tropical freshwater aquariums, a 64 litre, a 30 litre, and my newest addition, a 110 litre Juwel Rekord 800 which I set up a few days ago.
I read about 'instantly cycling' aquariums by adding media from established filters to the new filter. The site I read this on said if you do this you can add fish immediately. I was a bit dubious but thought if I kept testing the water for ammonia, nitrites and nitrates, and doing regular water changes anyway it would help. I did this with my 30 litre when I got it 2 or 3 months ago and it worked great, I keep my beautiful male betta in there and he's very happy and active! :)
So I did this again when setting up my 110 litre; I added sections of both carbon and regular brown sponge to the new filter - big mistake!! I had already added my fish to the tank the day before and they were doing fine, the water was clear etc. I realised the next day I had completely forgotten to add the established media so did so immediately. Before adding the sections of sponge, I rinsed them the best I could in aquarium water from my 64 litre tank (which has been set up around 5 months). On switching the filter back on, it spat out a load of cloudy water and that seems to be when the problems started. The tank water went a bit cloudy but the fish seemed fine during the next few hours so I decided to leave them for the time being and went to bed.
When I got up the next morning the water was extremely cloudy and all the fish were gasping for air at the surface. I did a 50% water change and they seemed fine again, so I went to work. My boyfriend text me whilst I was at work saying he had checked the tank, it was really cloudy again and there was a dead sailfin molly and all the fish were gasping for air again, so he'd moved all the fish into the other two tanks (using various breeding boxes etc as temporary measures so the betta was separated and the larger fish didn't eat the numerous guppy fry I am currently keeping in my 64 litre).
Obviously there was a lack of oxygen in the tank but I am not entirely sure why, and want to prevent this from happening again. I have a few ideas as to the cause of lack of oxygen:
- I only have one plant in the 110 litre
- The tank may have been overcrowded
- There may not have been sufficient surface movement
- A combination of these!
Just to give you a bit more information, these are the fish I had in my 110 litre when the problems occured: 5 white cloud mountan minnows, 5 young golden mountain minnows, 6 guppies, 4 mollies (2 balloon, 1 sailfin, 1 dalmation), and 1 small bristlenose catfish. The sailfin unfortunately died.
When I got home from work I emptied the tank completely, took the established bits of sponge out and threw them away, filled the tank with fresh water, used stress zyme and stress coat, left the tank running overnight, and I have just added the 3 remaining mollies as I was concerned my other tanks are going to be very overloaded with the emergency measures!!
Really sorry about the long post, just wanted to supply all relevant information! Hope someone can help.