I have read numerous posts on this and other sites about appropriate set-ups for turtles. I think I have one now, but the smell coming from their tank is overpowering. Two or three weeks ago my two approximately 4 in sliders moved into a 55 gallon aquarium - it is about half full of water and has play sand as substrate. I have a Rena XP3 with the four filtration pads it came with, some biorings, biostars and the other levels are filled with Seachem's "matrix" for more biofiltration. I dechlorinate the water with a chemical dechlorinator and use seachem's "stability" to help establish helpful bacteria. This set-up has been fully together 1 1/2 weeks and yet every two or three days I have to do at least a partial water change because of the smell. I DO feed them in the tank (I really cannot feed out of tank unless there is no other way) The water looks clear...sometimes I hallucinate maybe a smidgen of cloudiness. I am about to tear my hair out though!!!!!! any suggestions would be appreciated.
Am I maybe expecting the bio-filtration thing to happen too fast? I read on a different site it can take several weeks to build up appropriate levels of bacteria.

I suggest taking out the sand. It serves no real purpose. It only serves as a place to trap food and waste and for bad, stinky bacteria to grow.

Turtles produce so much waste, and there is so much uneaten extra food that rots that trying to "deactivate" it with good bacteria is not enough. I do 100% weekly water changes on my 40 gallon tank which is where I feed my 6.5 inch turtle. He lives in a 120 gallon tank where I've been doing weekly 50% water changes on 60 gallons of water but it's not really enough either so I will have to sometimes do 100% water changes as I just can't seem to suck up all the poo. I totally clean out the filters weekly, and they are filthy. The filter in my big tank is custom made by me and should be plenty strong enough. Since I've been feeding him in a separate tank, it's made a HUGE difference in the cleanliness of the big tank.

How many 4" RES's do you have? If it's more than two or three, then the tank is overcrowded making cleaning even harder. You can't really treat a turtle tank like an aquarium unless it's humongous. You have to treat it more like a mammal's cage in that it needs total cleanings.

Good bacteria will grow in your filter but it will take 3 to 8 weeks to have a good bacterial growth in there. Even then, the bacteria probably can't handle all the uneaten food and turtle wastes. One thing I do after feeding my turtle is to use an aquarium net to net out all uneaten food after two hours. Before I did that, my 40 gallon half full was a total stench fest. I only have a Duetto in there now since I moved my bigger filter to the 120 gallon. In a week, even with the nettings, the Duetto is so clogged, it stops flowing. I don't overfeed either. My turtle hasn't been eating well though so he's been leaving a lot of food. He just re-starting eating pellets this week after not eating them for many months.

I think if you take the sand out and do weekly 100% cleanings of the tank and filter, it well help a lot. You will eventually need a larger tank though. Even if you have the best filter in the world, it can only do so much.

Good luck!

I agree with Robyn; remove the sand. In fact, I think the best thing for turtles is nothing but the bare, glass bottom--no sand, gravel, rocks, etc. Anything where water can't circulate just encourages anaerobic bacterial growth, which are the ones that cause the nastiest smells. A plain glass bottom also allows the siphoning of waste materials. You might like to add aeration to the water, too, to encourage the good, aerobic bacteria. With my hatchling tank, that has six turtles (about 3 inch size), I found that adding activated charcoal to the filter system works very well. I don't have to change the water but once a month or so and the water stays clear with no odor problems. Also, give them lots of floating and submerged plants.

Don

Thanks guys. It seems to be under control now - its been a whole week without a smell - cleaning the tank weekly was what I expected - every other day was getting to be quite the chore though! I have two turtles in the tank now and expect to move in the next year to an area where I can have an outdoor pond for the fellows to move into when they get larger!

I'm glad things are better. So, what did you do to get it under control? Did you remove the sand? Good luck with your turtle pond!