How to store RO water for the aquarium

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Fishfunn

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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.
 
It was my understanding, that RO water has no nutrients to grow anything… I’m currently using straight RO stored in. Food grade translucent 35 gallon drum, out of the light, and I add straight RO, been doing so, for 8-9 months, and no growth in my drum… I expect, if you are getting a growth, it’s coming from the water you a blending with
 
It was my understanding, that RO water has no nutrients to grow anything… I’m currently using straight RO stored in. Food grade translucent 35 gallon drum, out of the light, and I add straight RO, been doing so, for 8-9 months, and no growth in my drum… I expect, if you are getting a growth, it’s coming from the water you a blending with
Have you rubbed the inside of your container to see if it is slimy? A friend of mine who owns a fish store told me to store only RO, and it should be fine. It just makes it so much easier to mix with tap water before dispensing to tanks.
 
My drum is sealed, and out of the way, under a staircase… I can see the water level through the translucent drum, if there was any biofilm, it would have to be clear, as there is no algae, or discoloration on the drum, at any level
 
My drum is sealed, and out of the way, under a staircase… I can see the water level through the translucent drum, if there was any biofilm, it would have to be clear, as there is no algae, or discoloration on the drum, at any level
I dont see anything either; if I touch the inside, it feels slimy. I will sanitize the container again and put only RO water in it to see if there is a difference.
 

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I would honestly bet, any biofilm on the container, would be fine for fish and aquariums… and there may be some in mine as well… we wouldn’t want it in our drinking water, or at least know it… but my drinking water RO system, uses any epoxy lined steel pressure tank, and who knows the inside condition of that… we may end up with a film, on any system, unless we add chlorine
 
Mine is empty right now, as I just did big water changes…
 

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The slimy sensation in containers holding water is biofilm from microscopic organisms (mostly bacteria). It's generally harmless but it's a good idea to hose out (normal garden hose and tap water) or wipe out the holding container before filling it. This removes most of the biofilm and keeps things cleaner.

If the container is sealed after filling the water should remain fine and safe for years. It's a good idea to aerate water for 30 minutes (or more) that is stored in sealed containers or has been sitting for a while before using it in an aquarium. This gets the gas levels in the water back to their normal safe levels.

Generally any sort of food grade container should be safe to store water for long periods of time.
 
What is RO water?
Reverse osmosis water. It is made by pushing water through different types of filters to remove chemicals, minerals and nutrients. The end result is water that is pure like rain water.
 
I store my RO/DI water in several types of container. The most important are my 1 gal. jugs of which I have about 26. These come from buying freshly pressed apple cider locally or distilled water in the supermarket.. I clean the cider jugs out which involves some bleach and use them and the others until they leak. Next I have a 2.5 gal. plastic gas can only ever used for water and 6.6 gal, can for water. Add another 3 Home depot % gal buckets with lids.

I batch my water in one building and need to bring it into the main house for the fish. I need only 11 -12 gals/week. But I am now too old to carry 5 gals of water at a time. So I ferry it into the house carrying a 1 gal. jug in each hand.

I batch my changing water in a 20 gal. can next to the 55 gal. tank in which I use it. This allowed me to move the probes from the tank to the can so I can batch the changing water to the needed parameters for the tank. The monitor measures conductivity as TDS, temp. in F or C and pH. The TDS and pH can drift higher a bit each week by an inexact amount. So I batch according the need each water change.

I normally fill all the containers about every 4 weeks or so. All have tops and are stored closed. When I was selling at events, I would bring a number of the 1 gal. and 5 gal. cans of the water with me and also my portable RO/DI unit.

edited to fix 2 typos
 
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I believe any water will go real bad real soon without UV light or sanitizer, for Any kind of Water in any container. darkness and coolness implied. over 6 months and You can be sure that something is growing in there...

It might look at you when you open the container :alien:

Beyond that, to last t a couple years, for drinking water we use iodine + chlorine and ceramic filters... For multiple years. Sodium Dichloroisocyanurate is used for even longer preservation. but, yes it is a form of cyanide. It give an idea of the disinfecting power required to go long term.

I rinse and swipe my main tank as soon as it starts to feel slimy. And I only de-chlorinate the water I use just before I need it. The water in the tank remains with it's disinfectant all the time.

My city uses chloramine. And it still builds, and after a couple weeks it become yukky. So I keep it real clean real soon.

It's a lot easier.
 
I do not use dechlor. I have excellent well water. I store my RO/DI water for a max. of a month or so and I have no issues. I have been using it for my current 4 Altum angels for over 4 years.

The water is always indoors. The fish space is kept at 78F max. and the main house in the low 70s. I have never seen nor felt "slime" in any of the containers in which I store my RO/DI. The de-ionizing resin is going to catch ions like NO2−, NO3- or NH₄⁺. There are other ions being filtered out as well.

My RO/DI water is pretty much pure. Because there is CO2 in the water which creates acid, the water is never at 7.0 as there is also no KH. I do not put my digital probes into the changing water until I have mixed in the tap water. The digital monitor is not happy with 0 readings. I calibrate the pH probe using 4.0 and 7.0 solutions.

My system is 4 modules in this order of flow: Sediment filter --> Carbon --> RO Membrane --> DI (Deionizing resin).
 
I do not use dechlor. I have excellent well water. I store my RO/DI water for a max. of a month or so and I have no issues. I have been using it for my current 4 Altum angels for over 4 years.

The water is always indoors. The fish space is kept at 78F max. and the main house in the low 70s. I have never seen nor felt "slime" in any of the containers in which I store my RO/DI. The de-ionizing resin is going to catch ions like NO2−, NO3- or NH₄⁺. There are other ions being filtered out as well.

My RO/DI water is pretty much pure. Because there is CO2 in the water which creates acid, the water is never at 7.0 as there is also no KH. I do not put my digital probes into the changing water until I have mixed in the tap water. The digital monitor is not happy with 0 readings. I calibrate the pH probe using 4.0 and 7.0 solutions.

My system is 4 modules in this order of flow: Sediment filter --> Carbon --> RO Membrane --> DI (Deionizing resin).
So how do you add RO to your aquariums? Do you add it straight in, then add well water, or do you mix it first with well water before you add it to your tanks?
 
I have been using RO water for years in my 5 gallon container.. I store it is 2 liter soda bottles. Ro water doesn't go bad You can put it in a center and store it for a year and then just add it to the tank. But it is important to state that not all RO water is the same. Some RO filters are better than others and if you don't replace the filters when you should mineral content in the RO water can increase. You can monitor your RO filter output with a TDS (total dissolved solids meter. If the TDS meter reading starts to increase you might have a problem or need to replace the filter.

RO water don't have "no nutrients" it just has a lot less than regular tap water. Only lab grade deionizes water's no nutrients and the DI filters or some RO units don't come close Lab grade. Bacteria are a very small single cell organisms. Water with a TDS of 1 will have enough nutrients for algae or bacteria to grow. But regular plants would die in this water. But the amount of bacteria or algae that can live in RO water is very small because of the limited nutrients. I have never found any reason for using a UV light to sterilize RO waternever have I seen any evidence of of a bacterial problem in the tank after a water change. I also don't use a declorinator or any water treatment to the RO water. I only fertilize with calcium and magnesium to the tank after a water change.
 

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