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I've had a moving bed filter as the primary filtration system on my turtle tank for about 6 months. It is cycling and maintaining water quality very well. I have a couple of smaller Eheim canisters that I use to deal with the typical daily turtle debris in the tank in an attempt to keep as much of it out of the main filter as possible. One runs a surface skimmer and the other I use as a water 'vacuum'. I also have a sponge/sock on the main filter intake to collect debris.

I researched various ways to deal with nitrate and phosphate loads in the water. A moving bed filter is very efficient so it generates a high level of nitrates. As far as I am aware, neither nitrate nor phosphate is a serious issue for turtles because they don't breathe in the water. However, I still wanted to eliminate them as much as possible so my guy and gals would have as pristine water as I can provide for them. So I finally decided to add an algae scrubber to the moving bed filter system.

If you're interested, you can follow my progress here:

http://algaescrubber.net/forums/showthr ... mbo-filter

Please add any comments or questions about the moving bed & algae scrubber combo on that thread, as I may not see them here. Thanks.

Michael

Have you tried standard bio media before you decided to try the moving bed filter?

Yes. I had an Eheim Pro3 2075 on this tank for nearly 10 months with EHFI Substrat Pro. Worked fine until it blew out around the hose connections in the canister head after a routine cleaning. I then had a Marineland C220 and a Sicce Whale 120 at the same time, with both EHFI Substrat PRO and EHFI Mech. Worked fine. Cleaning the 2075 was difficult because it's so big. I had to empty the water out of it in order to move it. It has casters but it was used in a location where they were useless. The prefilter in the top of the canister was very difficult to clean the sloughed off turtle skin. I finally discovered that I could soak it in straight bleach and most of the gunk would dissolve. I now use a sponge covered with a media bag over the intake to prefilter. I have to clean every day or two, but it's quite easy to get it on/off and clean it.

I used multiple proprietary canister filters and most leaked at the main head gasket after a couple of cleanings. I actually added a layer of electrician's tape to the hard edge of both the C360 and C220 to get them to stop leaking. The 2075 was not repairable. The Sicce was in use for about 3-4 months and I had no problems with it, other than the media trays are too small.

What I find very attractive about the moving bed filter are: 1. no proprietary parts; everything is standard plumbing parts; 2. the plumbing is totally outside the water container; everything can be disassembled easily for cleaning and/or maintenance, including the entire pump; 3. no pressurized container, so no joints/seams to blow out; and, 4. the media is self-cleaning; any fine dirt that gets into the water container ends up on the bottom not in the media.

The only downside I can see for a moving bed is that it's very efficient and consequently produces lots of nitrates. Thus, my addition of the algae scrubber to remove the nitrates and anything else the moving bed might miss.

I use a phosban gfo reactor to handle the algae nitrates and it seems to do the trick. It is a piece of junk though and requires a lot of maintenance because it clogs all the time.

I thought I'd post an update on this project. Since last posting I've modified the MBBR filter plumbing to make it less noisy. I replaced the support and swapped out the poly tubing with softer silicone rubber tubing and suspended the pump. This reduced noise significantly, which was important because I am in the same room all day. Here's a photo of the new plumbing:

http://algaescrubber.net/forums/attachment.php?attachmentid=6226&d=1441662467

I can also report that the water-fall type algae scrubber is working well and producing enough algae each week to supplement feeding of snails, frogs and fish. No, the turtles won't eat it. The scrubber has already reduced phosphates to 0.0. Nitrates are still very high and I expect it will take a few months for the algae to get it down. But with the phosphate gone, that's what the algae is eating now. Here's a photo of a typical week's growth:

http://algaescrubber.net/forums/attachment.php?attachmentid=6232&d=1442120042

The only regular filter maintenance/cleaning I perform is to rinse the prefilter sponge and 400 micron bag every two or three days. This takes about 5 minutes each time since most of the sloughed off turtle skin gets caught on the nylon bag and only fine debris makes it to the sponge. I rinse the bag under water to get off the big stuff, then soak it in undiluted bleach while I rinse the sponge. Once a week I pull out the algae scrubber screen to remove the algae. This takes 10-15 minutes since I have to disconnect the wires to the lights and the water pump before removing the box and then reconnect after cleaning.

I made an interesting discovery. Turtle poop and/or sloughed off skin must contain a fair amount of iron. Over the course of several months, this stained the 400 micron bag a dark rust colour. I later discovered that bleaching only 'set' this stain all the more permanently into the fabric. I then discovered that salt and lemon juice removes the stain. So now I can keep the bag looking bright white and new! After rinsing and bleaching the bag, I sprinkle coarse salt into the wet bag and then soak it in a small container with pure lemon juice. I also squeeze the lemon juice through the fabric a few times while it's soaking. The longer it soaks the whiter it gets.

Oct26: I discovered that plain white vinegar can be used instead of lemon juice. Vinegar is a lot cheaper, but not as efficient. It requires much longer soak times to get out the stain. But because it's so much cheaper than lemon juice, I think it's worth it. After all, I don't have to do anything while the fabric soaks for an hour.

So, I've been intrigued by algae scrubbers for some time.

As I said, right now I have a 55 gallon main tank, soon to be larger, and a simp made out of the crappy 55 gallon that came with the cheap Craigslist stand.

Most of the sump is given over to plants and shrimp. The most productive plant is duckweed, that I feed my turtle. No algae in the sump, but I still fight it in the main tank.

If I were to put in an algae scrubber, would it likely mean I can't grow plants anymore?

The algae growing in the ideal environment of the scrubber will compete with other plants for nutrients. Because the algae would be growing under ideal conditions it might eventually out-compete other plants for both phosphates and nitrates. That said, the nutrient load dumped by turtles each day is significant and might be sufficient to enable both algae and plants to reach a mutually agreeable equilibrium. In the natural environment algae and water plants share well enough. If I were you, I'd test for phosphates and nitrates. Whatever is there is not being removed by your current plants and algae would go after that first.

It's not an either/or choice. You can control the algae growth in the scrubber by reducing the hours of light each day. If you buy/make a waterfall type scrubber you can also limit algae growth by turning off the water pump for several hours per day. Like any plant, algae requires light and water flow through. You can control both. The algae scrubber forum contains a wealth of useful information about buying and/or building various types of algae scrubbers and how to run them.

http://algaescrubber.net/forums

PS: Unfortunately, my turtles didn't like duckweed so much, but they really liked water hyacinths at $4 each!

I should have mentioned in my previous response that algae growing in your main tank is an indication that you have nutrients in your water, probably both phosphates and nitrates. Setting up an algae scrubber will force the algae to grow in the scrubber rather than in the tank simply because the conditions for growth are ideal in the scrubber. Not so much in the tank. Eventually, the algae growing in the tank will get so little nutrients it will die off. The scrubber, especially a waterfall type, will enable you to 'harvest' the algae weekly if you desire. Some fish, snails and maybe your shrimp will eat it. My RES won't eat it, but who knows?