Depth of solution makes a huge difference. Try blowing into a tube sitting at the bottom of 5 gallons of water and then try doing it at the bottom of only one gallon... That is if you're feeling like Mr sciency this evening. Path of least resistance sort of thing. I'm not sure how much of a factor tubing length plays though I expect it's not significant compared to how deep the air stone is. Chuck advised keeping solution a bit lower to get maximize dissolved oxygen levels.

Hopefully hvg will chime in.

I did the math and forced my genius ten year old to join in. "It's Saturday! Boo hoo"

.54 psi at the bottom of a bucket, for pure water. Add nutes and other solids, more psi. Multiply by 4? Too much for my puny pumps.

As the roots grow lower the solution level. Maybe take a few buckets off of DWC and just get all kratky up in that.

So your son is going to university for fluid mechanics next year huh. Congrats.

I have plenty to say on this but it's late here right now. I'll respond in the morning.

Hydro, as always thanks. You saved me time because I would have trimmed tubing to see if that helped.

So by your math, 2 lpm is approx half gallon/minute, or 30 gallons air per hour per gallon water. For a 90 gallon setup that's 2700 gallons of air per hour.

I can get by short term by taping the airstone tubing in place. The weight of the stones pulls them to the bottom and they stop aerating. But I need to get a pump quickly. And I looked it up...45 db is the noise level of a library. :)

90 gallons? Are you needing air for something more than the buckets you mentioned? 12 buckets isn't 90 gal. 2700 gal/hr would require at least 4 of the pumps I use.
Could you use your existing pumps for the plants in the system that don't need a lot of oxygenation like the leafy greens? Fewer buckets means more air. And then get a bigger pump for the others like tomatoes and peppers that need more?

I just measured the db of my pump at 3 feet away. It's 68 db. Not real loud but I am in a small room so it seems louder.

Keep in mind that the liters per minute per gallon that I go by is probably overkill by a lot of people's standards. Many say half that and do just fine I always just err on the safe side. Can't have too much air. And I keep a lot of my roots in the solution. I just don't want you to go spending a bunch based on what I say when you could probably get away with less. I have a habit of over doing things. Built an aquarium stand a while a back for a 20 gal tank, about 200lbs. It was strong enough to park a car on. Ha!

Let me know what you going to do before you buy anything, if you don't mind.

I have 13 buckets and a 27 gallon res for greens. But now that you mention it, the cheap pumps are putting out plenty of air for the greens and the single tomato bucket. I can leave those the way they are.

So really I just need a pump for 12 buckets...60 gallons. I don't imagine I will be expanding beyond that any time soon.

Maybe this:

http://www.ebay.com/itm/571-1746-GPH-Aquarium-O2-Commercial-Air-Pump-Fish-Pond-Hydroponics-Aquaponics-/262234708824?var=&hash=item3d0e681b58:m:mR5ah7u9FidhrIMxvx0vOrQ

It has a variety of power options.

Yeah, and it's not even 60 gallons. You're not filling them to the top. I average around 3 gallons of actual solution per bucket but I use net pot lids that are much deeper than dropping a 2 or 3 inch net cup into a flat lid so my water level is lower which as you found out makes for less water pressure pushing back on the air stones. Even a gallon can make a difference.

http://www.amazon.com/Hydrofarm-AAPA45L-20-Watt-Commercial-Outlets/dp/B002JPRNOU

That is the exact pump I use but for half the amount of buckets. You could use that but would have to split the lines off the manifold since it's only a six. 700gph vs the 48gph you're using. Massive upgrade. Then when your plants start developing nice root structures drop the water level down for less back pressure. You could even just keep the air stones higher in the bucket like you stated earlier when you're water levels are high but I don't think you'd have to do that with that pump even powering 12 buckets but you'll always have that option.

Small price to pay for healthy plants. I just harvested several pints of cherry tomatoes off one of my red robin plants. When you get to do that and not go buy them at the store it makes it easier to justify costs. IMHO.

Just saw your previous post. For around the same price as the one I have you could get 1157gph vs 700gph. Pretty sweet. No manifold though.

I wouldn't go any less than the 794gph for 12 buckets. $27 hard to argue with unless they screw you on shipping. Not sure what a manifold costs. It came with mine.

For that price I may get me a backup!

Yeah, I'm gonna go with that. I don't really need a manifold since my lines are all set up and split.

I want those tomatoes. My cherry tomato plant is 1" tall. :)

Edit: Pump purchased. It actually comes with an 8-port manifold, it's just hard to see in the pic.

Seems like a smokin deal though I would definitely have more faith in the reliability of the hydrofarm pump.

Quit killing my buzz. :)

I'm sure this will rock just fine. Wish I could get something with that much power... Even if it was twice that price it would still be cheaper than what's available north of your border

I got the new pump installed. Not the magic bullet I was hoping for, but much better.

It definitely can't aerate everything I have, so I blocked off 2 outlets., and it's able to aerate 12 buckets. The buckets at the end of the lines are considerably weaker so I have to pull the airstone closer to the water surface.

But the thing is loud as hell! No longer a serene escape.