Air Pump Flow Rates

[LauraFrog]

I'm redoing my fish area. My parents do nothing but whine about the increasing number of fish tanks, mostly because they're all plastic containers with a mixed up mess of whatever random filtration parts I can haul out of the box.

I have room for about four 15 gallon tanks, maybe slightly smaller. They will be plastic containers because I can't afford glass. They will be good quality ones though and will replace the garbage I have at present. I'm planning to attach an overflow to each tank and run the whole lot into a sump, then run one big filter in that and use gang valves to drip the filtered water through all of the tanks. I would also like to set up undergravels in them.

I've currently got a 23 gallon tank running on an undergravel, fed by one air pump. I'd like to ditch this one (put it in the spares box) and buy one good one that will run all of them. What sort of air flow rate would I be looking at?

Thanks.

 

[Colin_T]

Hi Laura

If you run a trickle filter/ recirculating system on a group of tanks then you will need some pipe work set up to feed each of the tanks. You mention gang valves and if they are big enough they will work. However, airline gang valves are too small and won't work. Most people use 1/2 - 1 inch PVC pipe and fittings and run it off a water pump like an Eheim Hobby or pond pump. I have used black poly pipe (irrigation tubing) and that works too. PVC pipe should be glued up and is less likely to leak when under pressure.

Many years ago we connected all the shop tanks up to a huge pond/ sump to give us more water volume and help keep the water cleaner for longer. It also made water changes a lot easier because we could gravel clean and drain the tanks, but didn't have to fill them up straight away, (they automatically filled up from the sump). When finished gravel cleaning we just topped up the sump. We ran a corner sponge filter in each tank to provide extra air and for when we needed to treat a tank. During disease outbreaks we would turn off the tap that was feeding the sick tank and leave the air operated filter to run. When the tank was cured we would drain most of the water out and turn the tap back on to fill it up.
Having an undergravel filter in each tank can be helpful but also kind of defeats the purpose of having a trickle filter. You can do it but I would have a sponge filter or just an airstone bubbling away in each tank to circulate the water and provide oxygen to the fishes. Have a thin layer of gravel in the tanks, unless you want to grow plants. When you do water changes either drain the sump, or gravel clean the tanks, then refill the sump with dechlorinated water.

As for the airflow rate of pumps, it is hard to say. Some pumps state they produce x litres per minute. But how much is that really? Also some pumps don't produce as much air compared to other similar sized pumps.
When using normal aquarium air pumps, I like to have one outlet for each tank. This means if something happens to a diaphragm or airchamber, I can split one of the other outlets and keep air in all the tanks.
Air pressure is also reduced by water depth. The taller the containers, the more pressure the pump will have, and the less air that will be produced at the bottom of the tank, (end of the airline).
I currently use Aqua One, Precision 9500 airpumps. They are twin outlet, quiet & cheap to buy. They also have a 3yr warranty, which is really cool. Although the warranty doesn't include wearing parts, (diaphragm, air chamber, flapper valves).
You could buy a blower, big air pump, but most are designed to run 10 or more tanks. They also use more power than a couple of smaller pumps.

 

[LauraFrog]

I'm paid to maintain a large tank in town and there is a bubble wall feature driven by a single hole Hailea air pump. It seems to be good quality and has lasted a long time, and it is very quiet. The one I've got my eye on is a similar design, four hole (so I would be using some gang valves) and about 800 litres of air per hour. Or so it says. It's only 10w, which is another reason I have my eye on it, my parents are whining about the power bill as well. I've offered to pay for my power usage about seventeen times, but they won't take the money... and then they keep complaining...

If I put a big pile of bio rings in the sump and then stuck a powerhead in there, would the high turnover of water in the sump (presumably about 800 litres per hour in a 30-odd litre sump) be enough to filter it? Or would I need to use an internal filter instead of a powerhead and put the water in there?

PVC pipes and aquarium silicone are the plan. Airline tubes are not wide enough for tanks of this size, definitely not. The rural town I live in has an irrigation supply shop, it wouldn't be too hard to find some suitable fittings. I would like to run undergravels because I've found it's easier to keep a stable pH when working with soft water like I am, and it would also cut down on my water changes. I'm planting the tanks because they'll help remove nitrates (which again means less WC) and are cheaper than fake plants for fish that require shelter - livefish is bailing thin val at $2 a bunch. Because they are outdoors the natural light should do them (val is growing fine in my other tank about a metre away) and I never bother with CO2, I overstock everything too much to risk pumping toxic gases into the water. lol

 

[Colin_T]

The next time a power bill turns up just grab some money and give it to your folks for the bill. Then go back into your room and shut the door. However, once you start paying bills tho the parents will expect money for all the bills

You can use bio rings/ balls/ spheres, sponges, etc in the trickle filter. Have a layer of fine filter wool, (Dacron) at the top of the filter to trap the sediment that comes out of the tanks. All the tank water drains through this before going into the sump and over the bio balls. A piece of sponge is also a good thing to have but not necessary. The sponge normally goes under the filter wool and the bio balls go under the sponge. The water passes through the finest materials first so most of the gunk is trapped in the top layer. This makes it easier to keep clean because you only have to remove the filter wool and wash it out.

An 800litre per hour pump probably won’t pump that much water to the top tanks. As the water goes up, the volume decreases quite rapidly. This is probably a good thing considering the size of your sump/ trickle filter. The sump must be big enough to hold all the surplus tank water when the pump is turned off. When the power is off the water from the tanks will continue to drain into the sump until the level in the tanks is the same as the overflow pipe. This excess water will sit in the sump until the power comes back on. If the sump isn’t big enough to hold the excess water you will get a wet floor and the pump could run dry when the power is returned.
It is a good idea to have a pre-filter on any water pump. This will stop foreign objects getting into the impellor and causing damage or premature wear. A big pre-filter will also act as a biological filter after about a month.

Undergravel filters shouldn’t make any difference to the PH. If you have soft water with little or no carbonate hardness, then you can put some shell grit, coral rubble or limestone in the sump. This will help buffer the PH and keep the PH more stabile. Alternatively use a rift lake water conditioner at a lowered dose rate to increase the hardness of the water.

 

[LauraFrog]

I think it's the acidification you get with UG filters... the creek water which I use is pH 7.2, hardness, like, 3 or 4. So if I run undergravels it becomes soft and acid instead of soft and all over the place, as long as I only do small water changes.

I'm planning the sump with layers of wool and sponge in baskets and a prefilter is a must, no way would I go without it.

I'm not worried about paying bills really, they pay for my phone bill but that's only like, $20 a month, and I hardly ever use the house phone. And if they're worried about what I eat there's a problem with them! lol...

Going into the city this weekend, so with any luck there will be some decent containers... (AND some decent bettas. )