Aloha, Deejay-

Here's the deal with your waterfarms:

First to answer your question directly, you absolutely DO NOT need to put air stones in any bucket. Of course, you COULD, but experience has taught that the drip rings add enough aeration on their own, as evidenced by big healthy root masses you should see if you took care of your conditions. Adding more air never hurts, but huge harvests have been obtained without them.

The pain in the ass about Waterfarms is the modding you need to do to it to get it up and running(thankfully a 1 time thing). Buy the recirculating upgrade kit for each of the 8 packs you are running- or, if you are running just 4 plants, STILL get it. Look it up at the GH website to get a better idea of how it works. You are going to also want to add an on/off valve between the controller and the reservoir above so you can detach them from each other for cleaning and draining of the system. Drill more holes in the bottom of the red buckets that hold the Hydroton. This will greatly reduce the incidence of root problems(small enough so the Hydroton doesn't fall through,though.

If running the at least 4 buckets that have been linked in a circuit and modded as per the instructions at the website, get a more powerful air pump for the recirculator. gotta keep that solution mixed and ph balanced.

I'm not at all knocking GH nutes (referring to the 3-part flora series and additives), but their products tend to clog up their own systems. Those nutes cause a LOT of salt buildup (YES, even when flushing weekly). It is NO FUN at all to have to clean your drip ring or feeder line when you are in the middle of flowering, from under a trellis at the back corner of your room. This is no pimping of products and GH is great, but specifically for the Waterfarms, those nutes cause too many troubles. AN's line (bloom A/B (not connoisseur), Big Bud, Bud Candy, etc- the chem ones)has been shown to not have this problem- those of you out there who know, know, and it is a welcome relief to not have to worry so much about clogs.

If you aren't using any kind of organic nutes, and if you aren't already using Hygrozyme in your system, I suggest adding 35% food grade H2O2 to your rez at a concentration of 3-5 ml per gallon once after you flush and refill the rez. Thats about 40-65 ml into your 13 gallon rez. I hope you've installed that on/off valve so you can mix your nutes in there before draining them to the controller! Add the H202 first to the water and let it stabilize for 30m-1 hr, then add the nutes, mix, wait, then check ph, adjust, drain into controller. Once the rez has emptied into the controller, it is time to refill the rez. Plain pH'd water only! You don't need to add more nutes if you flush your system weekly. As a great grower once mentioned, the ph can be fine but the plants could still have salt buildup prohibiting their feeding of particular elements.

Put a little submersible water jet in the top resevoirs. Run 24/7.

OH--- flushing was a huge pain in the ass till a remedy was discovered at Petco. They have aquarium pumps 25' long using 1/2" tube with an on/off valve that connects to a sink nozzle. The beauty about this is,the hose is the exact size to fit over the coupling in the grommet in your control bucket. With a twist of the plastic, and by turning on the water in the sink, you are able to both fill and drain your system fully and effectively(no need to elevate your bucket sites). They cost $50 at Petco/Petsmart etc. That is one of the BEST things you can buy for your system. They really make flushing a piece of cake.

Hm, what else? The farms are cool and work well once modded, particularly if you are growing trees, or are doing a scrog (unless your hard-to-access lines get clogged). There is another fellow by the name of Heath Robinson who you may be interested in checking out-he's got a vertical grow that is so dialed in it appears virtually maintenance free and despite the oddity of its appearance, seems very simple to construct. It has got to be one of the most brilliant setups I have ever seen. Its the one that is silver and looks like a ufo inside- might be on rollitup.org or ICmag--- dunno.

best of luck-

La Dottoressa

--- and remember that with any mod you choose to do, try your best to simplify it as much as possible-- I see so many great mods on here, but a HUGE amount of them are so labor intensive, when there are much simpler alternatives.
Think, read, read more, read still more, and then ask questions- repeat ad nauseum