Canister reactor

Lately I've been seeing a little bit of cyanobacteria in my tank, so I did some H2O tests and sure enough, my nitrate and phosphate levels are a little high - not scary high, just a bit higher than I'd like. So I decided to try something I'd heard before - make a phosphate reactor from an RO pre-filter canister, since I had an extra lying around. It's a very simple concept, and technically, you can make almost any kind of reactor this way. Depending on the media you may need to tweak things, like put the reactor on your RO top-off line for a CA reactor. Since the phosphate media requires no special conditions (like low pH for CA) you can just pump straight aquarium water through it.

The idea is to run water through the canister in reverse to the way you normally would when hooked up to an RO system. To accomplish this, first you install a piece of PVC pipe in the center of the canister where normally the carbon block or sediment filter would go. Drill some holes in side of the pipe toward the bottom for the water to flow through. The media is then put in the canister around the pipe. Since the water will flow in reverse through the canister, it will enter at the top of the pipe and flow out through the holes in the bottom of the pipe, then upward through the media (flowing upward agitates the media slightly so it doesn't clump - this is especially important if you're using really fine media like FeO which will turn into a brick if it's not adequately agitated). Flow rate is controlled by a ball valve on the inlet line to the canister.

Here's a diagram:



and a photo of the unit in my sump.



I'm currently running SeaChem PhosGuard beads. So far it's running fine after a couple of days. Time will tell if it is actually effective.

What kind of pump are you using on yours? I'm considering getting a better pump since the one I have is a really weak one I had laying around.

It's good to see other people have used these reactors successfully.

Mike, let me know if you build your own. I can cut you some flanges on the cnc router

Edited by tcfab - December 17 2011 at 9:16pm

Mik3B-
I run kalk in mine by hooking it up directly to my top off line. I've done this for several years but I think I may switch over to an actual kalk reactor. I don't measure the effluent, and currenlty I just dump in a half a cup of kalk every couple months. I wish I was adding more which is why I've been working on getting the actual kalk reactor on there.

Adam

I don't know which direction may be best for each different media type, but I'm guessing backwards is best for most. I run mine backwards so that the water flows up through the media, slightly stirring it along the way, whereas I don't think you'd get that stirring if it were flowing the other way.

Thanks for the Tip, I had one and used clear hose in the middle and always had trouble with it, I'll use PVC, so smart.  do you use a gasket or anything at the top of the pvc pipe in the middle?