ro di storage tank

[backpack]

So I was at my grandmothers farm and noticed a water system she wasn't using. It had a 120 gallon fiber glass wrapped reservoir. Its rated to 125 psi. So I asked why she capped it and she told me the horses broke the line. She told me to take it. So tomorrow im grabbing it for fresh ro. I have two brutes as well. How can I use a auto shutoff like people do for the undersink ones? Do you just leave the system sealed to build preasuare or do I need a check valve oher than the one a brs unit comes with? I figured I would have the 120 auto fill hen fill the two 44 gallon brutes for mixing salt or extra fresh for my freshwater tank.

 

[AZDesertRat]

I would plumb the tank so it fills with RO only water. RO/DI is extremely agressive and will eat the rubber bladder in the tank given time.
You would then pull water from the pressure tank and feed it through the DI resin for making DI water. You would need to regulate the flow though as resin needs good contact time so you would make DI at around 1 gallon every 5 minutes or so, faster than the RO/DI makes water but still slow enough for good resin contact time.

If your RO/DI does not have a ASOV presently you would plumb it similar to this but the DI circuit would be a little different:
http://spectrapure.com/huds/4-STAGE-DWK-RODI-NAG.pdf

You could still have the DI on the pressurized tank side but would want to make sure and keep the flow low.

The reason you always separate the DI from the RO drinking water is the small 3-5 gallon pressure tanks tend to have problems with TDS creep since they start and stop constantly due to the low volume of water stored, with a 120 gallon tank you should have at least 80 working gallons I would think so it would not cycle as often and TDS creep would be a minor issue.

 

[ReeferBob]

I would plumb the tank so it fills with RO only water. RO/DI is extremely agressive and will eat the rubber bladder in the tank given time.

I've never heard this at all. Could you point to a source that explains why RO/DI is corrosive? It seems to me that it has less stuff in it then plain RO so I don't understand how it could be more corrosive.

 

[AZDesertRat]

RO/DI has been stripped of all its ions, minerals etc. so is trying to get back to its natural "dirty" state and will agressively attract anything it can to become dirty or neutral again. This is why you never use metals, expecially copper and brass, around RO/DI, distilled and even RO only water, it will literally eat the metal away. Some things like very high end stainless steel, titanium and tantallium are more resistant but will eventually break down too.

The captive air, bladder or pressure tanks have a rubber air bladder in them that will also be attacked by the water. RO only still has some TDS so is a much better choice to store in the tank and the bladder should last for years but will still eventually be attacked, you will see the TDS rise and sometimes see black discolored water once the bladder finally gives way. I have seen and had many small 3-5 gallon bladder tanks fail over the years on RO only systems.

 

[backpack]

This reservoir doesn't appear to have a bladder. Its not one of the pump resevoirs. Its from a water softener system that keeps 120 gallons in reserve so it doesn't have to keep up with the rate of use and cycle constantly. I purchased this ro di system BRS 4 Stage Value RO/DI System - 75GPD - Bulk Reef Supply, should I just take the di out and buy another carbon or sediment block?

 

[AZDesertRat]

Is the 120G tank pressurized or at atmospheric pressure? If it is pressurized it has to have a way to contain air since you cannot compress or pressurize water by itself? If it is non pressurized you will need to drill a hole in the side and install a float valve or two holes and install high and low float switches and a solenoid valve which would be my preference. You would then need a hole somewhere near the bottom where you would plumb a 1/4" line from the 120G tank back to the DI canister to make RO/DI water.

You would install an autoshutoff valve (ASOV) on the RO/DI system and plumb it to either the float valve or the solenoid valve so when the tank is full the RO system shuts off and either when the float drops or the lower float switch triggers the solenoid on the RO starts up again.

You would leave the RO/DI canisters configured as is. Take the 1/4" line that leads down from the RO housing to the back of the DI filter though and use it to fill the 120G tank.

The 120G tank probably needs a good cleaning if it held well water or salt brine water for the softener. Does the tank have any brand and model numbers on it to find a type or pressure rating?

 

[backpack]

Well I fixed the water system so I didn't take it. But two brute cans with a asov and a float will still be nice.

 

[ReeferBob]

RO/DI has been stripped of all its ions, minerals etc. so is trying to get back to its natural "dirty" state and will agressively attract anything it can to become dirty or neutral again. This is why you never use metals, expecially copper and brass, around RO/DI, distilled and even RO only water, it will literally eat the metal away. Some things like very high end stainless steel, titanium and tantallium are more resistant but will eventually break down too.

The captive air, bladder or pressure tanks have a rubber air bladder in them that will also be attacked by the water. RO only still has some TDS so is a much better choice to store in the tank and the bladder should last for years but will still eventually be attacked, you will see the TDS rise and sometimes see black discolored water once the bladder finally gives way. I have seen and had many small 3-5 gallon bladder tanks fail over the years on RO only systems.

Thanks! That makes sense.