Dear Larry:
Yes, sir, using sponge filters to provide biological and mechanical filtration in conjunction with a crushed coral substrate can be a successful set up for your classroom aquarium if used within the limitations of such a system. I would recommend including an inexpensive hang-on-the-back external filter to provide chemical filtration and additional water movement whether or not you can round up a HOB protein skimmer.
If you provide a HOB filter that is properly sized for the given aquarium, it should be able to provide sufficient water flow and circulation for your seahorse tank without the need for additional power heads, sir.
Regarding the water circulation, if the filtration system is turning over the entire volume of the aquarium 3-5 times per hour, then the water flow and circulation in the aquarium should be in the right range for seahorses. So for a 30-gallon aquarium, for example, you’ll want to look for an external filter that puts out about 150 gph. That would produce a turnover rate of about five times per hour (150 gph/30 gallons = 5), which would be ideal.
However, you should be aware that filters don’t always produce the water flow indicated by the size of the water pump they include, since things like head pressure and clogged up filter media can significantly reduce the water flow. For this reason, it’s a good idea to measure the actual output of the filter you have chosen when it’s mounted on the aquarium to determine if it’s producing adequate circulation.
There is a simple way to calculate if the water flow from your filter(s) and/or power head(s) is suitable for the seahorses or not. All you have to do is collect the outflow from your filter (or a powerhead) where it normally enters the aquarium for half a minute and then measure the water you have collect. Collect all of the water that the filter or powerhead puts out for 30 seconds, measure the volume of water that you collected, and then multiply that by 120. That will give you the actual flow rate for 60 minutes or one hour, with no guesswork involved. Then you can divide that number by the capacity of your aquarium to see how many times the tank is being turned over every hour.
For example, if the filter in question puts out 1-1/2 gallons of water in 30 seconds, multiply that by 120 and you see that the filter is pumping out 180 gallons per hour (1.5 x 120 = 180). Then if you divide 180 by the capacity of your seahorse aquarium (say a 30 gallon tank, for example), you’ll see that the filter would be turning over the entire volume of this particular aquarium about six times every hour (180/30 = 6). In this example, that would be a perfectly acceptable amount of circulation for a seahorse tank.
As you know, you typically want the filtration on a seahorse tank to be turning over the entire volume of the aquarium 3-5 times every hour. In my experience, I would say that a seahorse tank is under circulated if it doesn’t turn over the entire volume of the aquarium at least five times an hour.
However, if the filtration produces turnover rates considerably in excess of five times the volume of the tank every hour, then you need to start to be concerned about generating too much water flow and too much current for the seahorses. If you have a spray bar return or waterfall return that diffuses the output from the filter, then you can often achieve turnover rates of 10 times the total water volume of the aquarium every hour without producing too much turbulence and overpowering the seahorses in a tall tank. But if you don’t have a spray bar return or waterfall return that splashes the output from the filter into the aquarium and attenuates the water flow, then turning over the volume of your aquarium much more than 5 times every hour may produce currents that can overwhelm the limited swimming ability of the seahorses, so be careful about increasing the turnover rate too much.
Best of luck finding just the right filters for your seahorse setup, Larry! Will get you started on the training program off list right away, sir.
Respectfully,
Pete Giwojna
Ocean Rider, Inc. is an Organic Hawaiian-Based Seahorse Aqua-Farm & Aquarium that Follows Strict Good Farming Practices in Raising Seahorses and Other Aquatic Life.
