Reptile & Amphibian Forums

not sure if this is the right place for this or not but......
what kind of filter do you guys think would work best for a 50-60 gallon plastic pond outside housing two turtles. i currently have to change the water every week, huge pain, cuz i only have a small tank filter i use in the winter(inside tank). I've read something about underwater UV lights to keep out the alge and bacteria? thanks.

>I've read something about underwater UV lights to keep out the alge and bacteria? thanks.

Don't use UV sterilization on a fresh water system........

By the way Algae and Bacteria are actually good things to have and are part of the filtration process, and make oxygen.

I would just get a pond filter and do large water changes every week. If you really care about excess Algae you can use chlorine.

Search pond filters on Google...........
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Jeremy

"I am become death, the destroyer of worlds" July 16, 1945 Robert Oppenheimer

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UV sterilization is okay for fresh water. Most of the time it's used to eliminate suspended algae. There are a lot of high end indoor fresh water aquarium filtration units that incorporate UV sterilization. For your needs I would simply check online with some sources like Drs. Foster and Smith or similar outlets to see what they sell in the way of a submersible pond pump. Your pond as you describe it is not very big, so you don't want to plunk down some filter that takes up a ton of space in the pond. Find the smallest submersible filter that will filter up to 3 to 5 complete water changes per hour.
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Matt Campbell

"I only went out for a walk and finally concluded to stay out till sundown, for going out, I found, was really going in." John Muir

>>UV sterilization is okay for fresh water.

Not if you want the natural biological filtration to take hold and continue to break down Ammonia into nitrates and nitrites.

Otherwise UV sterilization essentially makes safe drinking water in a fresh water system.

see the thing with the alge is that the water gets green enough that you cant even see inches below the surface.

>>Not if you want the natural biological filtration to take hold and continue to break down Ammonia into nitrates and nitrites.

The UV sterilization only kills the water borne algae cells which contribute to 'green water' and other water clouding conditions. I a filtration system you typically have mechanical, chemical, and biological components. The mechanical consists of the first layer of foam or floss that the water initially passes over when first arriving in the filter. This removes all the larger particulate matter - ie. broken down plant matter, undissolved food, feces, etc.. The chemical portion of the filter usually consists of activated carbon or a combination of carbon and zeolite. Both are minerals used to draw in and fix ammonia and other water borne toxins that build up as a result of the breakdown of animal waste and/or decay of uneaten food or rotting plant matter. Finally the biological portion of the filter consists of a substrate of some sort that supports the growth of beneficial bacteria that breakdown of ammonia. The biological portion of the filter is often a coarse sponge or material with high surface area like bio balls or some similar material or something like expanded ceramic pellets. Once a filter is well-established and has a living colony of bacteria growing in it, it will continue to function and filter wastes as long as it doesn't become overloaded. The addition of UV sterilization simply adds an additional water cleaning capacity that kills microscopic things like algae which are too small to be screened out by the mechanical portion of the filter and thus remain suspended in the water column. At no point does the UV sterilization affect the rest of the filter because the UV bulbs are contained within sealed compartments and the water usually passes through those compartments usually after the filter but before returning to the tank. Having UV sterilization after the filter insures that all the largest particulate matter gets screened out first so that the bulbs are much more likely to be able to sterilize water that is mostly free of large amounts of waste and other gunk that would lessen their effect. At no point can UV sterilization affect the healthy operation of the biological components of the filter. In most herp related applications, UV sterilization is not necessary, but it can help eliminate cloudy water caused by algae. However, rampant algae growth is often a symptom of an imbalance in the aquarium filtration. Often when there are no live plants present you'll be more likely to get algae growth which respond to nitrate/nitrites in the water, whereas a healthy population of live plants often keep nitrate levels in check in the aquarium/pond and as such algae blooms are uncommon. However, many aquatic herps destroy or eat live plants and live plants can be tricky to keep alive especially indoors in an aquarium. But, that's a topic for another posting.
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Matt Campbell

"I only went out for a walk and finally concluded to stay out till sundown, for going out, I found, was really going in." John Muir

You can apply all the filtering techniques you want, you'll still have to do partial water changes weekly, and a full water change from time to time.
You will need mostly mechanical filtration, get the kind of filter that uses a pleated paper cartridge, buy an extra filter, and let it soak in a bucket of water and bleach solution to clean it until the next week, where you do a partial and rotate the filters again. I used a pair of magnum 350 canister filters with the micron paper cartridges, but that was for a bigger pond. For 55g, you could get away with one, but you will need to do partial water changes. No matter how well you filter urine, it's still urine. I also used a pair of heavily modified H.O.T. 250 aquiarium pumps for this, they take the same filter, you'll most likely need to relocate the intake and output so they aren't so close together. If the turtles are small, you'll need to keep the water fairly still so they don't have to fight the current, otherwise they won't make it.
My magnums were awesome, water changes were easy, shut off the pumps, swap filters, move hose away from pond, turn on pump until the level gets low, then turn on the garden hose until the water was at the proper level. If you don't add any chemicals to the water, the paper cartridge acts as a bio filter, and as long as you have some surface agitation and a some water movement, you'll have clean water until the filter plugs up and slows down the water flow. If the filter slows down too much your bio filter starves, your movement stops, and the water turns bad in a few hours.