# Sponge filter / Air pump



## waterlilly (Aug 22, 2010)

I have always used HOB filters in the past and don't know anything about sponge filters and air pumps. 
I want to get a hospital tank going (2.5 - 5 gallon, not sure yet). What air pump do you recommend? I don't want too much water movement because it will most likely be for bettas or sick fish.


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## hp10BII (Apr 23, 2010)

If it's just for a hospital tank, any air pump would do. It's ok if it's rated for a higher tank i.e 20 gallons, you can buy a valve to bleed off some air. Are you planning on running the hospital tank 24/7 indefinitely? If you are, I'd spend a little extra for a quieter pump. Tetra whisper, Fusion - their cheaper models would be rated for small tanks. Eheim if you want something quieter, but likely 4x the cost. Just a few examples.


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## TomC (Apr 21, 2010)

I have Fusions. They are pretty quiet.


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## Mick2016 (Jun 16, 2016)

I use a 20 TETRA WHISPER for a 10-g tank. If you position your ear close to the pump, you will hear a slight purring sound. With a fully open valve, the air bubbles it makes for the tank are louder than the pump itself. Very pleased with it without issue in two years.


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## waterlilly (Aug 22, 2010)

Has anyone used Pawfly? I saw on Amazon it comes with check valve, tubing and air stone.


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## hp10BII (Apr 23, 2010)

Haha, just bought one of their huge 2" round air stones off Amazon. Well made, well constructed piece, but I haven't tried their air pump.


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## hp10BII (Apr 23, 2010)

I think I seen the one you're looking at. A few things, you may need a little bit more output to drive a sponge filter especially if you use the check valve. A check valve will provide more resistance so maybe something rated for 20 gallons might be a safer bet. I don't know if there are replacement rubber diaphragms available but at that price, it's cheap enough to just buy another pump.


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## waterlilly (Aug 22, 2010)

hp10BII said:


> I think I seen the one you're looking at. A few things, you may need a little bit more output to drive a sponge filter especially if you use the check valve. A check valve will provide more resistance so maybe something rated for 20 gallons might be a safer bet. I don't know if there are replacement rubber diaphragms available but at that price, it's cheap enough to just buy another pump.


Yeah, that's why I have been staying away from sponge filters in the past. It seems so complicated and technical. I love my HOBs. So when using a check valve, any pump rated 10 gallons wouldn't be strong enough? I don't want there to be a lot of water movement and it's only for a 5 gallon.


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## hp10BII (Apr 23, 2010)

It's not really that complicated, hob's can be more finicky. I've used over 4 different hob's and each one has their quirks. A sponge filter either works or not. A check valve just stops the water from back filling into and damaging the pump. That would occur if the air pump is placed below the water line and there's a power failure, for example. A check valve provides more resistance so it requires more force to reach your sponge filter/airstone. You don't have to use the check valve.

A regular air line valve can control how much air is pumped into your tank. I think there's a pawfly pump rated for 50g for just a couple of bucks more. It comes with adjustable airflow which means you don't need a regular air line valve. But I have no experience with Pawfly pumps, but from what I've seen they make value as well as higher quality products. If it's for a hospital tank, you don't need to pay $$ to get things working. 

So whether that pump rated for 10g is strong enough with/without a check valve, who know's? Manufacturer tolerances can make it weaker/stronger. But I'd always go for stronger instead of weaker. A weak pump is useless, it may not even blow enough air, a stronger pump can have the air bleed off with an airline valve or a pump that has an adjustable air flow.


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## waterlilly (Aug 22, 2010)

Got it, thanks, hp10BII. Lots of great information.


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## TomC (Apr 21, 2010)

For a 5 gallon, pretty much any pump will do. If you don't want to use a check valve, situate the pump above the water line.


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