I'm late to this discussion and you've already purchased a canister type filter, but better late than never.
Maybe because canister type filters have been around for awhile and people are familiar with them they seem to be the recommended type on this forum. There are, however, filters that do a better job of cleaning your water, require less cleaning and maintenance and either cost much less or can be built relatively easily.
I have a 110 gallon Home Hardware stock tank for my 3 RES. I originally had an Eheim Pro 3 - 2075 canister which worked well for several months and then started to leak around the hose connections in the filter head. Actually, after a routine cleaning, it started spraying out water like a firehose. I spent nearly $500 for that filter and here I was looking at replacing the entire head! That would have cost me nearly as much again to replace because the rest of the filter is just a 5 gallon square plastic bucket and the pump and all the plumbing is sealed in the head. This was a manufacturing defect acknowledged by Eheim, but I was too late to get a free replacement head. So I pulled the 2075 and put a Marineland C-220 and a Sicce Whale 120 on the tank while I figured out something permanent. That turned out to be a do-it-myself MBBR (Moving Bed Bio-Reactor) filter in a 5 gallon pail with a Gamma-seal lid. I later replaced this with first a 10 gallon and then a 20 gallon Brute garbage can in which I added a water-fall type algae scrubber. I discuss the project here:
http://algaescrubber.net/forums/showthread.php?3368-Moving-Bed-amp-Algae-Scrubber-combo-filterMaterial costs for the MBBR part of this filter cost about $100 (garbage can, water pump, black ABS pipe, 1" hose and various ABS connectors) and it has maintained the water quality just well as the Eheim 2075 with a lot less cleaning and maintenance required. ALL the plumbing parts can be purchased at any well-stocked hardware store like Home Depot. MBBR filters require adding air to the water to increase the efficiency of nitrification. Any air pump can be used for this. I inject air at two inputs in the input hose connector. Nothing is proprietary. Here's a photo of the plumbing:
http://algaescrubber.net/forums/attachm ... 1441662467Note that all the plumbing (hoses, pipes, pump, etc) are outside of the water container for easy cleaning. The pump can be dropped offline by simply closing the two shut-off valves and opening the two unions. The interior of the water container (Brute garbage can) can be cleaned easily by draining the water through the input hose after removing the pump. For an MBBR filter, cleaning the water container is an annual or semiannual task. I also have a pre-filter sponge on the intake hose. This is covered with a 400 micron bag to make cleaning the sponge easier, which I have to do every two or three days. As you know, turtles dump a lot of debris into the water and it's easier to rinse the nylon bag and soak it in bleach than get all that debris out of a sponge. With only fines getting to the sponge, cleaning the sponge is a 5 minute affair.
I added the algae scrubber to remove phosphates and nitrates. I think the algae also raises the pH. Turtles do not breathe in the water, so removing nitrates is not necessary as it would be for fish. I'd like to maintain the water as pristine as I can, though, so I added the scrubber. The traditional way to remove nitrates, of course, is changing water. So if you can do that, there's no need to use an algae scrubber. But if changing large amounts of water every week in a big tank doesn't appeal to you, then an algae scrubber is a very good alternative.
I purchased LED light panels and a pre-built acrylic box from Expressions LTD here:
http://www.expressions-ltd.com/Algae_Scrubber_ATS_Box_p/ats-box.htmThe items I purchased from Expressions LTD cost about $300. If you can work with acrylic you could build the box yourself. You might also find cheaper alternatives for the LED panels, but their price is quite good because it includes wiring and controllers. So all this could be built with generic off-the-shelf supplies.
I also have an MBBR on my big fish tank and a couple of small algae scrubbers I purchased from Santa Monica Filtration. I plan to build another algae scrubber of my own design for the fish tank and move the two small scrubbers to other smaller fish tanks that would benefit from nitrate removal.
Best wishes for you and your turtles.
Michael