Air pumps, there are many different types of airpump, some better than others
From the top, the budget Piston driven pump , next is an example of a top class hi blo diaphragm and lastly on the right a range of budget Hailea Diaphragm operated type. Al of these can be used but I would keep away from the piston driven type unless you have earplugs and stay on top of a mountain, or deep, deep in the woods, cos they are fuckin noisy
the hi blo pumps are great, work well and are reliable too, I would recommend them, they are a little noisy but no where near the piston type. the bottom hailea is a smaller pump just punting out 10l/min, but would be enough for a small 2 pot system
All of these are noisy to an extent, but can be suspended in air, or placed on a square of acoustic matt, as used in sound booths, to deaden the noise a bit
So your plants life require oxygen rich water in order to remain healthy and grow. Pumps are also handy to run air stones
An air pump can help by injecting air directly into the water via an airstone.
Aeration is especially important in warm tents, when water holds much less oxygen. Altho this wont be a problem for you, because you WILL have a chiller, right/?
SPECIAL NOTE: when using more than one airpump in conjunction with a common manifold there can be a need to balance air distribution evenly, often still necessary when using stones of the same type and size.
This is very simple to achieve by the fitting of valved manifolds or single minature 4mm valves .....BUT.........I would not use these personally, as they put more strain on the pump, which will lead to its early failure. Instead, all I do is keep ALL of the airstone hoses the exact same length. This will ensure that each pot is receiving an equal amount of air to the root zone.
I ALWAYS make sure to locate the airpump above the level of the nutrient in the totes. ALSO: If you have no choice other than to site the Air Pump at a level below that of the water in your pond remember you will need to fit non return valves. If at all possible i would advise to always try to site the pump at a higher level (above the water). Your pump will always perform better without non returns (They do add extra back pressure to the system) More back pressure = less air .
Where to site the Air Pump
I recommend to site the pump in a well ventilated dry and cool place., preferably outside of the tent.
Try wherever possible to site the pump so it draws in fresh air. If the pump is situated where high concentrations of Co2, say from flowering plants inside a tent, the co2 will inevitably be transfered to the water, and your plants root zone - not good.
There are no hard and fast rules on what size air pump to go for, but I like big ones, I like big air pumps too lol.
As an example I used a 60litre/min one in my 4 pot system and a 40l/min in my 2 pot system, but again, the more the merrier.
I have used everything from 40l/min up to 180l/min pumps, all dependant on system size, but although nice to have and very much beneficial in plant development, you don't actually NEED them with a recirc system like those described in my first post. they are beneficial tho, in that they keep the foots floating in the tote, and deliver dissolved oxygen enriched water directly to the root zone. If placed appropriately they can also help prevent roots migrating down return pipes.
. Next up, AIRSTIONES.
Again airtones come in many different forms, here are a few varieties. See below.
These are just tools to disperse the air within the pot/ tote, to distribute it in a more efficient way to the roots.
The bottom pic is not an airstone, it is an air diffuser, which provides micro bubbles, and is my favourite of them all, but they aint cheap, and they have to be "hard wired" to your tote, meaning cleaning them is a pain in the arse.
The other stones shown all have their merits, but I also preffer numbers 2 and 4 above, the toblerone shaped ones and the cylinder with square ends type.
The discs I am not so keen on, because they lose half the surface area to plastic (on the bottom of the stone), and a weak pump will not pump air thru all of the stone, with more coming from the inlet side of the stone.
They all have their pros and cons,
Picture Number 1 - cylinder type XL stone, these are tricky to get standard hose on to, because the inlets are bigger than normal, but they work well, and are easily cleaned.
Number 2. toblerone type, provide a good spread of bubbles, and are good beside return outlest to keep roots at bay. down side is they break easily if disturbed
Number 3. classic disc type, ok, they do the job, but lose efficiency if the pump isn't up to it, but then they all do so maybe that's a bit unfair.
Number 4 Same benefits as No. 2, but can rattle in the totes, which is a pain if you are trying to sleep in the same room.
Number 5, Norres diffuser- the bollox for air bubbles, its like a Jacuzzi, downside is it needs a big airpump to run them properly (60l/min minimum for a 4 pot system.
There are other types, golf ball style, ring type etc etc, they all work to a degree.
I ALLWAYS ditch airstones after 3 grows, and I allways clean them after each and every grow, including the airlines. It doesn't take much (a warm water/ bleach mix, a new pot scrubber and / or some isoprpropyl, or Hydrogen peroxide does the job nicely.)
Like I said earlier, air pumps and stones aren't really a necessity for a simple recirc system, but if there is more DO on offer, it would be rude not to take advantage of it eh? in my opinion.
I'm no expert, and am willing to be corrected on anything which you may think is incorrect or misleading, or if you have anything to add, feel free.