lost my cycle

[Lady Hobbs]

Good idea from everyone here. But I would still check that pH just in case. Admittedly the tank was neglected and a neglected tank can have a pH crash. That would cause the ammonia to rise although it would be less toxic than ammonia in a higher pH.

Obviously Oscars do not like a pH of 6 but if the pH was dropping gradually, they may have simply adapted to it. I think adding media would help and better maintenance but it only takes one second to check the pH just as eliminate that as a cause?

Good luck. Hope you get back on track.

[Indian Woods Angels]

125 gallon tank using one canister and a sump using 14x10 x12 area of bio balls as bio media is undersized in the amount of media the system has.

Bio balls are not very efficient. You need around 3 sq ft of bio balls on a 125. Or a much more efficient media. The problem is that more efficient media often has a more compact pore size and plugs easier.

The canister you have is not really set up for big fish, if you want to use it as a media filter it will plug all of the time because of the detritus size it is trying to work. Put a sponge filter with a decent sized porosity on it's intake so it can not pull in the big junk, wash this sponge out a lot, like every three days or per the restriction on the canisters discharge flow rate.

I would add a filter such as a magnum 350 to be used as a base filter for pulling these large detritus loads from the tank. This will help to keep the other filters free of all of this large junk. I would not even worry much about establishing a bio in the magnum, just use it to pull the big poops and uneaten food debris from the tank. Clean it a lot like every three days or so minimally so it does not dose ammonia into the tank from all of the big junk.

They are like having dogs these big fish. And just like a dog they have the business to contend with.