Aerate RO water?

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Feb 19, 2013
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I didn’t want to highjack another thread. I did not find much info on this topic within the forum or online and specific to orchid growing. I wanted to create a clear thread for discussion.

I’m interested in learning if others aerate their RO water reservoirs. I understand the benefits of aerating rain water or tap water.. my interest is specific to RO water. Does anyone in the forum currently aerate their RO reservoir? And if so, what do you use.

If not, what is the reasoning? Would love to learn more about this and give it a shot if it’s worth the effort.

Is aerating a reverse osmosis reservoir beneficial for growing orchids?

Aerating a reverse osmosis (RO) reservoir can have some benefits for growing orchids, but it is not always necessary or beneficial in every situation. Let's explore this further.
  1. Oxygenation: Orchid roots require oxygen for healthy growth. Aerating the water in the RO reservoir can help increase the oxygen content, which may be beneficial for the orchids' root systems. Adequate oxygenation can promote root health and prevent issues like root rot.
  2. Temperature regulation: Aeration can also help regulate the temperature of the water in the reservoir. Some orchids are sensitive to temperature fluctuations, and maintaining a stable temperature range is crucial for their well-being. Aeration can prevent the water from becoming stagnant and overheating, especially in warmer environments.
  3. Algae control: If the reservoir is exposed to light, aeration can help reduce the growth of algae. Algae thrive in still water with access to sunlight. By agitating the water surface through aeration, you can discourage algae growth and maintain a cleaner reservoir.
However, it's important to consider the following points:
  1. Orchid preferences: Not all orchids require highly oxygenated water. Some orchid species, such as those naturally found in high-moisture environments like rainforests, may prefer more stagnant water conditions. Research the specific orchid species you are growing to understand its requirements better.
  2. Humidity considerations: Orchids often benefit from higher humidity levels. Aerating the water in the reservoir can increase evaporation, potentially lowering humidity levels in the surrounding environment. It's important to find a balance between aeration and maintaining adequate humidity for your orchids.
  3. Water quality: Reverse osmosis systems typically produce high-quality, purified water. However, excessive aeration can potentially reintroduce impurities or gases, such as carbon dioxide, into the water. This reintroduction could affect the water quality and potentially harm your orchids.
In summary, aerating an RO reservoir for growing orchids can provide oxygenation, temperature regulation, and help control algae growth. However, it's important to consider the specific orchid species, humidity requirements, and potential impacts on water quality. Monitoring the orchids' health and making adjustments based on their individual needs will help ensure optimal growing conditions.
"ChatRWB" response:

RO water, when exposed to air, absorbs carbon dioxide, resulting in the formation of carbonic acid. At today's 4% CO2 level, that results in an equilibrium pH of about 5.2-5.3.

I cannot see how bubbling air through the water will oxygenate it. Yes, you are creating a greater surface area of the gas-liquid interface, but what you're bubbling through it has no "extra" oxygen. There are systems available to fishermen to bubble oxygen through the water in their live wells, and it does keep the fish alive and livelier longer, but the "superoxygenation" stops the moment you stop the O2 flow.

Ditto with "temperature regulation". If the water is in an open-topped tank, evaporation will cool it a bit. Bubble air through it and that increased surface area will enhance the evaporation, cooling it more.
Who suggested that aeration of water would be beneficial? Nothing further can happen to the water once it is in equilibrium with the surrounding air.
Ray's points about oxygen and temperature are spot on.

The main action from aerating water is that you move it and it is a very energy efficient way of moving water when you don't need to pump it any height (I used to have a 5,000 gallon pond run entirely on air lifts).

This movement will stop water being stagnant can prevent bacterial and algal films growing on the surface of the water but may just mean you get them suspended in the water column or on the walls and floor of the container. Having pure RO water won't stop growth as cyanobacteria can fix nitrogen and then others can use that.
As far as I know, a reverse osmosis system will not remove any dissolved gases from water. There are some other filters, e.g. a 0.22 µm filter used to remove microbes, that also will remove gases but those filters have nothing to do with reverse osmosis.
On a related topic, aerating DI water is highly suggested (by me) since it appears that the O2 has been stripped from the water when leaving the filter. Just my observation and informal conclusion.
I just realized that you wrote DI, not RO, water. Sorry.
But it is the same with DI water, no gases are removed during the process.
….and even if they are, unless you’re storing in a sealed container, the water will quickly come to the equilibrium solution of each of the gases in the air.
I would aerate. The very depth of the storage vessel means the greater concentration of oxygen is near the surface (the atmospheric interface) with diminishing levels further down the water column. Where is the outlet in the storage? In the anoxic zone.
I use a 65 gallon tank that is a white/clear color. I pump water to this 65 gallon tank from the cistern.
-Right now I am still using a 300 watt aquarium heater to heat the water. Rain water stored in an underground cistern. If I didn't use an aerator the water will be at 77 degrees at the heater (on bottom) and various cooler temperatures in the tank. With no aeration, the heater cuts off because I suppose it heats the water around the heater and reaches the set temp. Aeration makes the entire tank the same temp.
-The white/clear tank grows algae without aeration. Maybe it is the agitation from aerating, but the algae growth is stopped or slowed down considerably. Yes, I now wish I had bought a black tank.
-Y'all can argue about it, but I think there is SOME benefit...
Kind of like Ray saying "There is some benefit to using a wet wall in high humidity"
I would aerate. The very depth of the storage vessel means the greater concentration of oxygen is near the surface (the atmospheric interface) with diminishing levels further down the water column. Where is the outlet in the storage? In the anoxic zone.
Unless something is using the oxygen in your tank and there is no diffusion of oxygen within the liquid it is impossible to get an anoxic area in the bottom of your water butt.

I have a water butt connected to an outflow from my pond that each year gets some escapee tadpoles in it. No aeration but those tadpoles thrive at all levels!

Anaerobic zones in tanks and small water bodies are caused when there are lots of rotting debris at the bottom of the container and happen in this debris. Directly above them there will be a good amount of oxygen. Aerating this will stir that up and prevent the anaerobic decay happening but hydrogen sulphide and other things will be released when this is first done and you'd be better cleaning the container!

Aeration is an efficient way of moving water but will not force extra oxygen into the water or perform other miracles! Oxygen generators will add extra O2 when on and for a period afterwards but whether that has a benefit to orchids grown in highly aerated media seems to be a matter of opinion.