Sometimes the simplest things work out best. Here is a good example.
For a planted tank, a canister filter is the widely recommended choice. And it is easy to see why. However, there are some disadvantages to canister filters:
- the cheapest ones will still cost >$50 (not talking about a "mini" here), with prices going up to $400+ for the latest Eheim.
- however small, anything that lifts water over the tank rim has a potential of emptying out a large tank in minutes. Hope you are around when that happens. Also, canister filter inlets can be deadly to smallish creatures.
- going through the (clogged?) input strainer, the water runs up the tubing, through x elbows, bends, and kinks, into the filter housing, down to the bottom, up through (around?) the various media, further through the impeller housing back into the tubing, up to the rim and out into the tank via spraybars etc. All of this creates friction, turbulences, or just simple blockage, which is made up for by added wattage.
- as convenient as they are, cleaning still involves a lot of steps, well you probably know.
- to use a canister filter for dissolving CO2 gas, an inline reactor is a good solution, still, it needs to be built or bought, and somehow be plumbed into the flow.
So here is an idea which removes these disadvantages, plus offers a great way to dissolve and distribute CO2 without having to construct an inline reactor:
- the pump which I used (AC30) costs between $15 and $20. A big piece of sponge comes in at $5. I cut that in four, the quarter is big enough to filter my 36 gal tank for several weeks:
- no risk. 'nuff said.
- here is where the internal filter shines. The AC30 uses 6 or 8 Watts (will check this later) and provides plenty of flow for my 36 gal tank. Compare that to 20 or 30 Watts for the average canister filter.
Also, the filtration is outstanding. The sponge (that's the nature of the beast) fills up very very very evenly. After a few weeks the flow goes down, and it is amazing how much stuff comes out of it! Since we are using a solid piece of foam, that's a lot of capacity even when compared to a large canister filter with "pads".
- I have the sponge sitting on top of the pump. I just lift the sponge off, use some sort of dish to catch the dripping water, and off to the sink or (if you clean in tank water) bucket it goes.
- an airline is connected to the powerhead so the CO2 bubbles are smashed up by the impeller into fine mist, dissolving on its way to the surface. I get more CO2 into the water with this setup than in my 10 gal where CO2 bubbles into the AC Mini. Surface agitation (lack of it) is big part of this, but it also tells me that all the CO2 gets dissolved.
So what are the cons?
- Need to find a pump that doesn't mind sitting upside down. For example, an AC50 got very noisy when running that way. The AC30 I have works great for a couple of months already. Absolutely no noise (I have to look into the tank to make sure it is running). Of course you could put the pump on top of the sponge, but that would make cleaning a little more involved.
- Visual impact - there is some trade-off here... instead of an inlet and an outlet pipe, you have a pump and a sponge sitting in a tank corner. In a corner tank, having it sit in the corner, covered by plants... totally invisible. Depending on your scape, you would need to think about how to hide i. Many obviously don't care about showing some tech stuff so maybe it doesn't bother them. I prefer covering it up with plants.
Can not think of any other disadvantages... what do you think?