Is there a reason you need 4 outlets?
For a 400 gallon fish tank, you want an air pump that can deliver at least 1 CFM (cubic foot per minute) of at at 2 psi.
You don't necessarily need special plumbing to hook up air pumps. You can get the nylon barb and threaded fittings at lowes or the hardware store and you can use regular PVC plumbing and ball valves to get from the air pump to where you need the air. I usually put a threaded ball valve right at the edge of the fish tank and put a right angel barb fitting with thread tape so the barb points down and I only need to use enough flexible tubing to get from the barb fitting down to the air stone and this helps avoid kinking or smashing the flexible tubing. I'm simply using one big air stone in each of my fish tanks, just make sure it is appropriate to handle the amount of air you want it to deliver.
Here is where I got my air stuff, might be a bit costly but you can get info from there then go price shopping.
And since you are in Florida, I would recommend you stop by Aquatic Eco Systems some time and at least pick up a catalog even if you are not buying anything. The catalog is a great resource. I'm using a couple of their air pumps one is a TL40 and the other a TL66 they both use the same replacement part kit. They do need their diaphrams and air filters replaced probably yearly.
The TL40 would supply a good amount of air and has the outdoor housing. If you are installing this in a protected location or inside, you can save some money but the other air pumps might be louder but the LT19 would supply enough air for you too.
I would only go the linear piston pump if you are likely to suffer a catastrophic fish kill if the air pump looses efficiency and it takes you a day to notice and replace the diaphragms. I had my air pump diaphragms go on the big system and it got along for about a week before I was able to replace them. Now I keep a spare replacement kit on hand.
Keep in mind my system has a bit of redundancy since the water pump runs constant providing aeration to the fish tank and I stock fairly lightly. If the power went out while the air pump (which is on the battery backup) was limping, I might have had a problem but I was lucky I guess.
This time I want a good one. Not an emergency but I am thinking ahead because mine is a cheapo and I understand that it is good to have a backup.
I use these air stones. They come in 3 sizes and sink to bottom of tank and have good bubbles pattern. Use a lot in hydro. Fish like to play with them (push them around). Hope this helps.
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The little battery backup AZOO pump is only going to provide a tiny bit of air looks like .07 cfm from each output so that is a total of 0.14 cfm which I would estimate to be enough for perhaps a lightly stocked 50 gallon aquarium. You could probably do better to get a good inverter and deep cycle battery with charger and get a bigger air pump.
FYI I see 30 catfish in a 300 gallon tank as very reasonable stocking but by no means low density seeing as catfish can get very big.
so how much air do you really need, that is the question?
The duckweed tank when it is only being used for duckweed and no fish, wants very little air, one of the air stones from the AZoo pump would probably take care of it when no fish are in residence. When you have fish in it, I would give it 0.5 cfm of air since when doing quarantine you may be dealing with stressed fish and perhaps salting so extra air would be good for them. =.5
300 gallon fish tank I would give between 0.75-1 cfm= 1
For a total of 1.5 so far
I would need to know the size of the raft beds to know how much you need for that but I think an air stone delivering 0.5 cfm every 4 feet is pretty common in rafts beds or you might do more smaller air stones to spread it out more but still deliver the same amount of air. Now those recommendations are for rafts. If you were to arrange your DWC so that the plant cups are suspended in boards that are supported above the water surface instead of floating on it, you won't need to supply as much air since there will be greater water/air contact at the surface but some air will still benefit the plants in the raft beds.
Now I'm not an expert in raft culture, I've resisted it for the most part so I hope people with more experience will chime in with recommendations for you. I have done some DWC hydroponics though and the plants definitely did far better when I added more air and I wasn't even doing raft, I had the plants suspended over the water. Anyway, I think you will need something bigger (or more than one) than the bigger of the high volume low cost air pump or the TL66, the question will be if you want a single bigger air pump or small blower or if you want multiple smaller air pumps
So how big/how many are your raft beds? And keep in mind you can always blow off extra air into the sump tank as aeration only counts as too much when the start bubbling the poor fish to exhaustion or boil them out of the tank.
I'll have 4x 150 gal DWC tanks with 'rafts' suspended over the surface, not floating. I was planning on just one airstone per DWC tank.
The AZOO pumps would only be to give me a little more buffer time to get a backup generator going (I would not leave this filled and connected, normally). I'm not convinced that buying and maintaining a deep-cycle battery, a charger and an inverter is really worth it for me. The fish are a small part of the operation. I would like to be able to save them if possible in the event of a power outage, but I think it's worth the risk of losing a batch every now and then to avoid buying and maintaining all of the complicated (and failure-prone) backup options. What do you think of this? I would hope that one or two AZOO backup pumps would give me at least a few hours to deal with the situation. If I was pumping 0.28 CFM of air into the 300 gal FT with 30 catfish, any guess how long they might survive?
Anyone here have experience with these AZOO backup air pumps?
It's looking like I might need both the TL66 and the TL40 then. This is getting expensive!
I'm curious to hear what people think of the linear piston pumps at the bottom of that page (those that often run for 8 years.. !). More expensive, but worth it?
Finally, TC, do you not like the cheaper air pumps I linked to above? Their 6-month warranty worries me..
I've never handled the cheaper air pumps but they do sell the replacement diaphragms for them. But they sell the replacement part kits for the TL66/TL40 too though they don't feel the need to print that in the catalog, I wonder if that means something?
Now For about the price of both the TL40 and the TL66 you could get more air with the SL88 piston pump in one package for less wattage.
On the rafts, being told they are 150 gallons doesn't really tell me the size? For rafts to know how much air they need we are more interested in the square footage. Are they 150 gallon stock tanks with a cover over them full of plants? If so I might put 0.35 cfm of air into them. Most raft beds for commercial operation are around 4 feet wide and they often put a stone delivering 0.5 cfm every 4 feet. You might not need as much with the plant supports being suspended over and not touching the water but having plenty of air generally makes for good plant growth.
so if you were to put 0.5 cfm into each of your 4 DWC tanks, then that requires 2 cfm
And then 1 cfm for your fish tank plus 0.5 cfm for the quarantine tank. 1.5 cfm So a pump that can provide around 3.5-4 cfm at 2 psi should take care of you (provided you don't go adding a lot of stuff.)
The LT28 could do it though you would need to provide a protected place for it since it doesn't have a weather proof housing. This one pump could do it though it would use 130 watts and I would recommend getting a spare diaphragm kit for it. Remember that most diaphragm air pumps do need the diaphragms replaced regularly.
If you went with the low cost ones you would need two of the bigger ones and that would only just barely cover it and I don't know how reliable they are long term, if you go that way, buy extra diaphragms when you buy the pumps. That would use probably around 100 watts to run both of them.
And as noted above the SL88 piston pump could provide the air needed plus some, it comes in a outdoor housing and the wattage looks reasonable though the initial price is high, you shouldn't need to be replacing diaphragms yearly.
How much do those Azoo backup air pumps cost? Doesn't look like AES is actually selling them anymore and I threw out all my old catalogs.
how much air would you recommend (or what formula would you use) to figure out how much air is needed for say 90 lb of fish in that 300 gallon tank? (I through out this number since I found it was quite possible to grow catfish out that big in a 300 gallon tank in a year, I figured 30 catfish at 3 lb each.)
and seeing that Greener is in the desert, it could get quite hot, what would you see as the "DANGER" temperature at which keeping enough air in he water with the air pump might become nearly impossible and remedial action to cool the water might be needed.