Zoo Med Filter not what the Axies wanted?

I have two nearly full grown axies. I had been using a simple sponge filter and I wanted something that was better at helping with their "mess". I went out and purchased the Zoo Med 501 filter, did a 20% water change and put them back in their nice clean tank. By the next morning, my white one had lost off of it's beautiful red coloring in it's gills and was making frequent trips to the top. My darkie was also going up for air. So I added the sponge filter back in and by morning, all of it's color had returned. So now I have both filters going and happy critters. I just feel like it is an overkill, but I don't understand why the 501 wasn't adequate for them. Does the sponge filter add more needed oxygen? They are so much more active now too! Hubby says, go with what works and don't worry about it. ?

Perhaps because the zoo med one hasn't had the chance to grow any beneficial bacteria you will need to run the old one in parallel with it for a few weeks.

The beneficial bacteria break down the harmful substances excreted by your axies into less harmful ones and they can build up quite quickly if something interrupts this 'cycle'.

Quicky question - how big is your tank?

Run both for awhile. When the ZooMed kicks in biologically you can take the sponge out. Keep a back up filter close by for when the ZooMed stops running.

Got it! My tank is around 40 gallons I believe. I had a 20 gallon long when I started and this one is about double. I'll be honest, the 501 is not my favorite filter. Ok, I really hate it. It took me forever to even get the thing to work. I have the large Fluvals for my aquatic turtles and have NEVER had the issues that this litte thing caused. It is just so easy to keep the current down with it though. I contemplated taking it back several times, but now that it is working, I don't want to touch it! My tank is noticibly cleaner, but I still just don't like it!

Well its a lovely sized tank. It's surprising how quickly ammonia can build up sometimes ... Go with the advice you had here and post to let us know if you have any other problems ... or just post to let us know how you are getting on.

Welcome to the forum!

Thanks! I've been reading for months and have gotten a wealth of information. This one had me stumped.

The sponge filter runs on bubbles, right? If so, then there is a big difference in how much the two filters aerate the water. If your tank has a solid lid, you might want to consider keeping a sponge filter or airstone, even after the new filter is broken-in.