Im growing 2 plants in a RDWC and I was wondering exactly how much oxygen i should be supplying to my 2 plants by way of an air pump and air stones…I’ve read it should be 1part oxygen to 4parts water so basically should be 20ltrs/minute for every 100ltrs of water…is that correct?
I have a 90ltr rdwc( 2 plants in a tub each with 30ltrs of water each tub + 30ltr of water in reservoir) with a 20ltr/minute air pump that pumps 2 x 6cm round airstones and im wondering if that’s enough or if i need a bigger pump and/or airstones. I also have a 20cm round air stone but the pump I have can’t push air through it properly and I just get big bubbles on the edge of it. I would like to run 2 x 20cm stones if that wouldnt be too much?
So is what I have enough air/oxygen supply for 2 plants in my system?
I never read anywhere about how you determine the amount of air you need…I run single tote/reservoir setups and have 4 large 4x4 inch air stones in each tote…my general knowledge is that for the most part you cannot have too much air bubbles…
Conceptually speaking, the main goal of air bubbles is just to disrupt the surface of the water where the exchange of gases happen. You can’t inject or super-charge water with air. It can only hold so much DO at a given temp/salinity. It’s not like water takes on an extra molecule of oxygen. If it did, it would become hydrogen peroxide. Plant roots need Dissolved Oxygen (DO), which only enters water at the surface where water meets air. The goal of an air stone is to keep the surface disrupted and agitated, as a means of circulation… just like in an aquarium.
Calm waters lose DO as the plant consumes it, so keeping the surface moving is the goal. A splashing recirculating pump in the res has a similar effect.
You kinda need more air. There is alot of performance to be had by increasing the air in a dwc system. You can also add oxygen into the air tubes to benefit even more. When you do this (ad more air) be advised it is much better to run more multiple smaller stones than it is to run fewer larger stones. When you upgrade from where you are at now you will definitely notice a difference. You want there to be tons of tiny bubbles like fizz in the water
The lack of info on this aspect of dwc is why I decided to ask this forum as I’ve spent hours searching for answers but not much out there.
I’ve also got the impression you can’t have too much as long as it isn’t disturbing the roots too much so I’ll definitely be upgrading as I don’t want overwatering issues due to lack of DO which is what I imagine would happen if not enough DO?
I’m looking at either a 50L/min or 70L/min pump which I hope should be enough(but not too much) to pump 2 x 20cm round airstones.
A little off subject but another aspect I can’t find a definitive answer for…just varying opinions.
I’ve also read the distance between the water level and the bottom of the pots should be between 2"-3"…a have mine at 3.5"…is that an good distance?