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What do you think of this filter?

raymond82

Member
Hi,

A while ago I was in a creative mood and I build myself a filter. It's a cylinder with a volume of 0.85 liters and I filled it up with lavarock. In the middle I placed an airlift with a small tube, the opening of this tube is all the way in the bottom of the cylinder, such that the water flows through the lavarock and then out of the airlift.


I know this is not an uncommon way to make a filter, but given the size that I uesed,
would it provide sufficient filtration for a 50 liter tank with a trio apisto's and some Nannostomus?
 

slimbolen99

Active Member
5 Year Member
Only experience I've had with lava rock was in a filter in an ornamental pond outdoors. What I found was that it easily clogged and was difficult to de-clog. It also, over time, broke down into 'dust' and therefore 'mud'. I think it would work; the exhaust tube probably needs to be pretty good size to move any amount of water (3/4" diameter minimum?). Best way to learn is to try it and experiment.
 

raymond82

Member
That's good to know about the lavarock, I'll keep an eye on it. I made this filter because I had the feeling the spongefilters that I normally use might clog too easily.

Right now the tube has a diameter of 16 mm or 0.6", water flows out but I couldn't get too much force behind it. I'll try to find something wider to see if it provides a bot more flow.

My main concern was whether ~0.8 liters of lavarock would provide enough filter material for such a tank.
 

gerald

Well-Known Member
5 Year Member
I've made similar filters out of all sorts containers, even a shampoo bottle, using small lava rock, bone charcoal, gravel, Poret foam, and various other media. Some of my lava rock and bone charcoal have been in continuous use for 20+ years. A tiny bit crumbles away when you wash it, but not enough to be noticeable, and with air-driven filters there's no impeller damage to worry about. Looks good to me, and that should be plenty of volume for a few Apistos and pencils. Volume of bio-media needed depends on the fish volume, not the tank volume. If you move up to a wider pipe, you might also need more air to push it. If your air pump capacity is limited, I'd stay with the small-diam pipe.
 

raymond82

Member
Thanks Gerald! Shampoo bottles, that sounds awesome!!

I'd like to stick to the (pond) lava rock, I bought a 15 kilo bag for 14 dollar, which is much better than the 20 dollar they charge for 1 kilo of substrate from an aquarium brand.

After replying here I reread one of your previous posts where you helped me out with setting up my other commercially available filters. There you also mentioned that a larger diameter pipe needs more air flow. This is something I want to experiment with, cause I don't have much air pressure. I think I'm going to make a couple more filters like this anyway, it's fun too!

I understand that fish volume is most important for filter volume, is there any rule of thumb or magic formula that can be used to determine filter volume?
 

sasikan

Member
was it not one inch of fish per gallon? i am not sure how this would relate to the amount of filter material that you wood need
 

raymond82

Member
Exactly, I think that's related to the water volume. In the metric system we say 1 liter of water for each cm of fish, taking that rule into account would be over stocking a little bit I think. I anyway always wondered if the rule would be the same for a discus and a pike cichlid....

With filter volume it mainly depends on the type of material I guess, since different filter materials have different surface areas. At least that's what you read in the packaging.
 

gerald

Well-Known Member
5 Year Member
Based on fish in the 2 to 3 inch (5 to 8 cm) range and "average" feeding, I would use a pint (1/2 liter) of filter bio-media (lavarock, gravel, or foam) for up to to 8 fish, a quart (1 liter) for 8 to 20 fish, a half-gallon (2 liters) for 20 to 40 fish, .. etc. Thats just what I've observed "works" for me over many years, not based on any calculations. More volume certainly wont hurt, and multiple filters per tank gives you more safety and flexibility than one filter. With growing plants you can get away with less filter volume. Those "length of fish per volume of water" approximations for stocking tanks are OK for small fish (4 inch/10 cm or less) but not for larger fish, since the food consumed and ammonia produced is proportional to their body volume, not their length. Two 5" fish = much more body weight and ammonia production than ten 1" fish.
 

raymond82

Member
Thanks Gerald, these look like nice rules to go by. Most of my aquariums are stocked with up to 8 fish, unless of course there is fry. All together I think the way I have it now should then work fine with 0.8 liters. This weekend I'll build a couple more filters like these and experiment with different sizes of outlets to see what that does to the flow. I think apisto's don't appreciate too much flow but of course water needs to run through the filter so I'll have to find a balance.
 
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