After some serious studying and reading reviews and such I bought the Petco ac-9903 two air line system with variable speed control been using it for a full 2 yrs now for worm tea and even some time in a hydro unit continues to work without fail. The variable speed comes in handy and I wouldnt want anything else. There is a Petco model better than the one I have a 9904 which may have 4 outlets not sure but it also has the varaible speed.

How is the noise level with that model?

If you just use one outlet its noisy. but by using both outlets not much more than a humm.

I've been leaving my castings loose and giving the bucket a stir a couple times a day and it has worked up a nice brew. I have two 2" air stones running. The tea has almost no smell so I take it that it hasn't gone aenerobic. I've had this batch running for probably four days and fertilizing the plants every morning with the tea. The four gallons is about half gone now, so I'm just gonna keep the air running till I run out of tea.

Be generous with your cutting of the airline. As it ages and you change stones you may need to cut an inch or so off of the end once in a while for a fresh connection. Also, it is good practice to keep your air pump above the level of the top of the bucket. Otherwise, when power is lost the water will siphon into the pump from the bucket. Another safety tip is to include a drip loop in the electrical plug so that water will not back track over the cord and into the outlet. Note: This should be a ground faulted outlet as you are dealing with water and electricity. I never heard of soaking air stones before using them. Note: Strangely, air stones do not last forever. Purchase extra. I so agree with purchasing air tube from a hardware store instead of the aquarium section of a store. Almost like totally different product.

I recently read about a study that showed that aquarium pumps just are not strong enough to handle 5 gallons in a way that will produce a lot of microbes. Maybe 2 gallons max.

I can't find it. So...Here is a quote from someone who really knows stuff, Tim Wilson on his "Microbe Organics" webisite:

"First of all I’d like to make it clear that most aquarium air pumps don’t produce enough air to use in a container larger than 1 gallon when considering making an aerated brewer. So don’t even try the 5 gallon pail with the aquarium pump idea everybody is passing around. You need a minimum 0.05 CFM (cubic feet per minute), open flow of air and an optimum 0.08 CFM per gallon (US) or higher to make aerated compost tea (ACT). ACT should have the DO2 sustained at or above 6 PPM. Generally, aquarium pumps produce around 0.02 to 0.16 CFM. Another generality is that 25 watts of power usually produces 0.75 to 1.0 CFM in diaphragm air pumps. The wattage is usually marked on the pump which will help you figure out the approximate output. I’ll cover more on air pumps later." - Tim Wilson http://www.microbeorganics.com/

I have the ecoplus/Eco 5 commercial air pump (793GPH, 4CFM), which is kind of standard among home brewers at the 5 gallon volume, and I've been really happy with it. But here is more from Tim Wilson on air pumps:

"A Word About Diaphragm Air Pumps: If you are going to buy a pump to run your aerated CT brewer I now (as of Feb 2015) recommend the Elemental line of commercial air pumps. Like ECO commercial air they are a combination piston and rubber (diaphragm) pump but they are quieter and seem to out perform the ECOs for the same price range. The Elemental 951 gph which we are using with our Mini-Microbulator outputs 2.5 CFM and the 1744 gph which we will be using with our 50 gallon airlift Microbulator measures an average 5.3 CFM (ECO 5 is 4.0 CFM). On top of that, these pumps are painted and it seems there is a higher standard applied to their manufacture. In the USA you can purchase this line through buildasoil.com. If there is enough demand we will sell these pumps in (from) Canada. I can also recommend Hailea 9730 pumps (2 CFM max.) which you can purchase from www.aquaticeco.com and other places. These are solid, long lasting pumps and I know other commercial brewers use them for 50 gallons but I just can’t recommend them for more than 30 gallons. If you use one for a 5 gallon unit it will last virtually forever.

"All of these pumps come with a little threaded brass fitting for screwing into the air output. DO NOT USE THESE! Put them in your parts drawer. These constrict the air and reduce your CFM by at least 20%. Rather, find tubing which slides over the nipple into which the threads are tapped. In the case of the Eco Plus 5 and the Hailea, 5/8ths inside diameter works. Slide the air tubing over and secure with a gear clamp. The Eco Plus has a very short nipple so I score the metal with a couple of swipes with a hacksaw to create barbs for the tubing to grip. You can find tubing at a building supply like Home Depot or Rona in Canada. I use the braided reinforced stuff which does not kink. Always try to keep your pump at or above the surface of the water so it does not siphon back if the power fails."

He also has very reliable ratios for your worm compost tea. And he advises that fewer ingredients yields higher results.

This is the aerated compost tea (ACT) recipe I have been using. It's not unlike his:

• 5 gallons of water. For tap water, bubble off the chlorine/chlorinate in the water with a few teaspoons of worm castings for 30 mins. Then add:

• 1.25 to 2 cups... of fresh Worm Castings. (Note: the more diverse the worm food is, the more diverse your microbes should be. I add it loose and strain later with a paint strainer.)

• 2 to 3 Tbsp... Kelp meal.

• 2 Tbsp to 1/2 cup ... of Alfalfa meal - but only if I can find the organic kind, without salt.

• 1 to 2.5 Tbsp... Molasses.

• 4mL ...of fish hydrolysate (NOT fish emulsion). Neptune brand is good

Hope this isn't TMI.