How to store RO water before aquarium usage

[Fishfunn]

I have a 30 gallon medical-grade food container that I use to store RO water in my garage. My garage gets hot, so I am wondering about the growth potential of harmful bacteria and fungi. When I make RO water, I do a 50/50 mixture with tap water for ease of mixing before dispensing to the other aquariums. I use an underwater pump that allows me to fill the aquariums.

Recently, I placed a UV sterilizer at the bottom of the container to prevent bacteria growth. If I leave a filled container of water sitting for two weeks or more, I notice that the insides of the container feel slimy, even though I don't see anything. I am wondering what this slimy residue is and if it is harmful for my fish.

 

[Fishfur]

I have a 30 gallon medical-grade food container that I use to store RO water in my garage. My garage gets hot, so I am wondering about the growth potential of harmful bacteria and fungi. When I make RO water, I do a 50/50 mixture with tap water for ease of mixing before dispensing to the other aquariums. I use an underwater pump that allows me to fill the aquariums.

Recently, I placed a UV sterilizer at the bottom of the container to prevent bacteria growth. If I leave a filled container of water sitting for two weeks or more, I notice that the insides of the container feel slimy, even though I don't see anything. I am wondering what this slimy residue is and if it is harmful for my fish.

The slippery coating is biofilm - mostly composed of bacteria, most of which are harmless. It is no different than the biofilm that coats every submerged surface in every aquarium.

One way to prevent biofilm from forming is to use a storage container that’s extremely clean and seal it tightly shut immediately after filling it - which will exclude bacteria and spores & dust, etc., from getting into the container.

Another way to combat biofilm formation is to use chlorine, just as it is used to keep our drinking water biologically safe.

Sufficient chlorine (bleach) added to the container of water will kill off bacteria but only for a couple of days as it is extremely volatile and will outgas quickly.

So you have to renew the bleach every few days. It isn’t a problem for the fish because water conditioner will dechlorinate it.

The biofilm isn’t typically harmful (it’s in every lake, river, stream, pond, fountain, etc., but it has a small potential to be harmful depending on just what organisms find their way into the container.

Water bowls or buckets for any pet will very quickly acquire layers of biofilm unless washed daily - in part because pets dribble bacteria laden saliva into the water when they drink which exacerbates the problem.

The films can taint the taste of the water to the point that a pet may refuse to drink it or make it smell enough that even we can detect the unpleasant odour.