Need some filtration assisstance

[flexmaster777]

Hi there everyone, I need a bit of help.
I've been in the hobby for about a year now. To date I have a 55 gallon (MAINLY) pleco tank. I am running a fluval 405 and a whisper EX20 tagged along with an air pump with two long airstones. I have a good amount of driftwood in the tank. My fish stock are of the following:
Amano shrimp, Upside down cat, Kulhi Loach, Horseface Loach (X3), Banjo cat(X2), Neon blue Stiphodon, Panda garra, Hoplo cat, African Dwarf frog, Flounder (X3), Rainbows (X5), Stingray plecos (X2), leopard pleco, Sultan pleco, goldy pleco, green phantom pleco, blue phantom, mustard spot pleco, inspector pleco, and a gold nugget pleco.

As you can see I have an over stocked tank with a couple of Java fern and moss to eat up nitrates.
The only issue I am having is getting nitrates at 20ppm. My feeding schedule is about once a day, I know that is too much but I can't help it. I do a water change about 70 percent once a week, while doing the water change I stir up my pool filter sand since I have the flounders, banjo cat, and the horseface loaches that digging in and/ or rummage through it. The problem arises when the poop gets stuck underneath, I do not want the poop to stay there and potentially make toxic gases that could be fatal for my fish. The issue is that during a water change I take out all the driftwood so that I can stir up the sand bed. I want to avoid doing that so I recently purchased Hydor Koralia X2 powerhead so the poop moves around and eventually gets sucked into the filter. Taking out the driftwood is a bit of a pain since I have to take it out and put it back it. Not to mention possibly hurting a fish (especially the diggers). I live in apt so I use a 50 ft python to do a water change and manually checking the water temperature to correctly adjust it.
Anybody have any advice/tips/comments?

[Atmichaels]

Hi Flex - welcome to the planet!
You said it yourself, you are grossly overstocked. In addition, you have species with different water parameter requirements. Just looking at temperature, the "stingray plecos" which I'm assuming are really sewellia sp. loaches should have a max temp of 24C (76F) whereas your sultan should be at a minimum of 25C (77F). This mix also has different dietary needs, among other things. I'm truly surprised the nitrates are your only problem so far. I think you need to reconsider your stocking and either add some tanks or rehome some of your fish. Probably not what you wanted to hear but it will help you and your fish in the long run.