I'm not sure about the cfm, I think that's a term to move air around a room. For air pumps, it's called liters or gallons per minute. For a 10 gallon container, a two outlet air pump with 4.5L/min. or 1.2G/min. should work just fine. But if you want to use the more is better technique, which I do here, then double it to 4 outlets/air stones per container. Hope this helps.

Don't bother with extensive maths here, with 10 gallons simply do like urbangardenfarmer recommends, use a standard air pump with two outlets, or even split it in two with a T-connector, and there you go.

Btw: there is quite a controversial discussion going on in a few forums about air stones and if they actually add or replace any oxygen at all to the nutrients. There are even a few theories about bubble size and which is best. Some claim that there is only an exchange of oxygen at the surface when it gets broken by the bubbles. I have read a few more or less scientific studies and expert's explanations but they still are contradictory and they all seem plausible but claim very different things, though. I really don't know what to believe. LOL

PS: I've build a nicely bubbling Air Lift that is pumping up a lot of water foam to the surface. But I still don't know what it actually does or performs on the oxygen level. I guess I need to get a dissolved oxygen meter to actually test it and know for sure!

I have a 6 outlet, 45 l/min. aerator. I have two hoses to each of 3 containers. Assuming even distribution, that's 7.5 l/min per hose or 15 l/min per container. Would one hose per tank be adequate? I should be able to split the outlets to service more containers. That is my goal- to increase the number of containers without purchasing another aerator or increasing electricity consumption.

BTW, I have air stones in one tank and hoses only in the other. I started them 2 weeks apart, but the one without air stones seems to be growing as well or better than the one with them.

As lucas formulas said an oxygen meter would be interesting.

One more thing. As a newbie I'm impressed with the hydroponics lettuce growth. I have a large container of lettuce sitting next to the first hydroponic container. The lettuce in soil medium was planted 3 weeks before the hydroponics container. The hydroponics container has nearly caught up with the growth of the other. The leaves are bigger and thicker. I'll harvest some tomorrow and will be interested in the quality of one vs. the other on the salad plate.

Mark

The air pump isn't a huge consumer of electricity. So little, that I can't be bothered to do the math. If it came to 5 cents a day, i'd be astonished.

I too, have been impressed by hydroponic growth rates. It's pretty awesome, eh?

I have a similar setup running for my nurseries, also a 6 outlet that comes as a air cooled mini electromagnetic compressor. Don't know how much l/min it delivers, have to check tomorrow as it is late here. Well I know that it consumes 35 w/h that is a little more than a standard 5w/h double outlet pump. If you're interested I can post a few pix of the airlift tomorrow as well.

Cheers,
Lucas

Lucas,

Pictures would be great. Mine is a 20 watt aerator.

Regards,

Mark

That 20 watt aerator, at and average of 8.8 cents per kwh costs $1.27 per month. Before I buy any appliance, tool or electrical equipment, I determine the operating cost. I'm really that cheap.

Take care,
Mark

That's funny Mark, but smart! Lucas has an interesting point. I've been wondering if a small water pump(40GPH) circulating in the reservoir, would have a better effect of aerating or keeping the nutrient fresh? Just in case you were wondering Mark, it uses 5.3 watts :~)

I agree that the water pump will run a lot of different wc's, but the piping makes it more permanent. Where as the air pump setups are easily moved back into the house for wintering. (for the perennials)

The mini compressor in the background at pic 2 uses 35w/h and delivers 50l/min. Here are the pics of the airlift.

A few explanations although it's a no-brainer: drill two holes (near bottom which is open), introduce the tubes and the two air stones from the inside. The lower tube is 1-1/2' I believe and then follows a reduction fitting to 3/4' and that's it! The styrofoam makes the whole thing float and keeps and stabilizes it vertically. If some-one wonders why, originally there was a T-fitting on top, that's why there are two of these semi-round cuts. The tube is short, that's because it isn't about pumping from the depth (or reaching some hight) but to have a max of flow.

PS: I mostly don't make exact calculations but if I deal with 5 watt I don't care, but with 35, I do. It's not only the cost but as a businessman I do it by principle ;-)

Interesting Lucas. Do you ever have issues with the air stones plugging up?.

I too have run a small business for 30+ years and I can't help myself. I am obsessed with calculating all the cost angles, even on a small hobby investment. Failure to do so means business failure.

Thanks for the pics,
Mark

Great idea! What is the other blue tube in the first picture?

It wasn't all my idea, it's actually taken from the "famous" airlift that is used in some setups and shown as a simple low cost air driven pump on YouTube. But there is no air stone(s) involved with those and it isn't about combining bubbling and flow. ;-)

The other tube isn't directly related, it's the upstream of a water pump. In fact the airlift is part of a nursery complex I've recently developed.

About clogging: I haven't been using air stones for very long as I gave preference to other systems until now. But I buy them very cheap and guess I'll simply replace them when clogged. I have got some of those flexible tubes also, but for some reason they do not deliver as much bubbles as the stones.

@ markmahlum, 30+ years here too as I started early and in a few branches since. I've heard that some people do grocery shopping without looking at the price labels, I couldn't do that for a single item LOL.... it's what they call a professional deformation, I guess. But as it is common among business people, I believe it doesn't need to be treated... The worst I saw was in Ukraine, though. Even the average Ukrainian Mobster spends half an hour on a menu to make sure that the dishes and drinks they order are worth their unlaundered money- not to mention that they pester the living daylights out of the waiters, for the very same purpose LOL.