RO water/TDS

[SSalty]

I only have an RO unit not a DI. My TDS is reading 5ppm. Can 5 ppm be bad for my reef tank? I know 5ppm is rather low, but I am just curious what your thoughts are.

[AZDesertRat]

Probably not. The problem with TDS measurements though is you never know for sure what the make up is. Its certainly better than tap water but for $40 or so you can add a vertical refillable 20 oz DI canister and cartridge and remove any doubts or worries.
What was the tap water TDS to begin with? This number will tell you how efficient your RO is.

[SSalty]

around 265. The thing that has been steering me away from getting a DI is because I am using a 4 gallon holding tank, and I also drink this water. I don't want to drink DI water and it is nice to have the 4 gallons on hand for top off and quick water changes. If I get a DI I would have to bypass the holding tanks. Is RO/DI water bad to drink?

[rustybucket145]

Get a DI!

[Toddrtrex]

Could always get some of those 5 gallon container to hold the RO/DI water in.

That is what I used. I always try to have one completely full one and one half way full one on hand, just in case.

These are the ones I am talking about,

http://i5.photobucket.com/albums/y189/toddrtrex/RO_DI1.jpg

[tkeracer619]

I have ~50gallons of pressure tanks. I also drink some of this water, you don't pass the RO through the DI untill after the tank anyways. They say it runs water too fast over the DI, I put a flow restricter before the DI to solve this.

[AZDesertRat]

I have a 14 gallon pressure tank myself. I store RO only water in the pressure tank and have a tee coming out of it so one side feeds my drinking water, ice maker and other RO uses and the other side feeds the DI so I can make over 10 gallons of DI at a shot without waiting around.

I keep five 5 gallon drinking water bottles full of DI all the time so I can do water changes and topoffs and then refill them from the DI unit.

[SSalty]

<a href=showthread.php?s=&postid=11083040#post11083040 target=_blank>Originally posted</a> by AZDesertRat
I have a 14 gallon pressure tank myself. I store RO only water in the pressure tank and have a tee coming out of it so one side feeds my drinking water, ice maker and other RO uses and the other side feeds the DI so I can make over 10 gallons of DI at a shot without waiting around.

I keep five 5 gallon drinking water bottles full of DI all the time so I can do water changes and topoffs and then refill them from the DI unit.

I am trying to picture how you have this set up. After the R.O pressure tank you have a line going to a spicket for drinking water, and a line gonig to the DI. Than when you need DI you run the water from the tank that has already passed through the RO and than you run that water through the DI?

[AZDesertRat]

Correct. I removed the line from the membrane directly to the DI so the RO feeds the pressure tank. On the line from the pressure tank I installed a tee and ball valve so it can go to the domestic uses or to the MaxCap dual DI system. The down side is slightly higher RO TDS due to TDS creep in the pressure tank but with the step up to the 14 gallon tank I don't short cycle as often as with a 3 or 5 gallon pressure tank. I also make it a point to completely drain the pressure tank at least every two weeks or so by filling up several water bottles at a time so I get a complete fresh low TDS tank of water to start out with again. It keeps the TDS creep to a minimum that way.

[MarkD40]

SSalty,

Why on earth would it not be O.K. to drink RO/DI water? I mean jeez man....it's WATER. If your TDS goes from 265 to 5 after RO and you have no problem drinking it then why would removing the remaining 5 ppm of solids make it unsafe to drink? It may not have much flavor but it is WATER! Several bottled waters on the market are just tap water run through an RO/DI filter.

[SSalty]

<a href=showthread.php?s=&postid=11084407#post11084407 target=_blank>Originally posted</a> by MarkD40
SSalty,

Why on earth would it not be O.K. to drink RO/DI water? I mean jeez man....it's WATER. If your TDS goes from 265 to 5 after RO and you have no problem drinking it then why would removing the remaining 5 ppm of solids make it unsafe to drink? It may not have much flavor but it is WATER! Several bottled waters on the market are just tap water run through an RO/DI filter.

Well, I have heard ALOT of mixed feelings about drinking DI water. It something that the DI filter does to the water which makes it un-healthy. I am sure someone who knows more will chine in.

[SSalty]

<a href=showthread.php?s=&postid=11083740#post11083740 target=_blank>Originally posted</a> by AZDesertRat
Correct. I removed the line from the membrane directly to the DI so the RO feeds the pressure tank. On the line from the pressure tank I installed a tee and ball valve so it can go to the domestic uses or to the MaxCap dual DI system. The down side is slightly higher RO TDS due to TDS creep in the pressure tank but with the step up to the 14 gallon tank I don't short cycle as often as with a 3 or 5 gallon pressure tank. I also make it a point to completely drain the pressure tank at least every two weeks or so by filling up several water bottles at a time so I get a complete fresh low TDS tank of water to start out with again. It keeps the TDS creep to a minimum that way.

So in other words, its not the best thing to have a pressure tank?

[shikhyung]

AZdesert, Now I understand what you told me before. I followed intruction from the flilter guys' pic, no wonder after the initial DI canister capacity, the water only dripping . So put a T after the pressure tank. BTW, (sorry, change subject for a second) my dual TDS meter at input DI saild 165, and out is 000. Seem to be good, but the resin looks like changing color so fast. .., its 1/3 of the way so far. I think I just used about 15 gallons the most ( included rinsing and flushing at the begining). any idea? Shin.

[AZDesertRat]

Pressure tanks can add TDS due to TDS creep when an RO first starts up. When you have the tank and an autoshutoff valve it cycles on and off frequently to keep the pressure tank satisfied. When you make water manually you can flow to waste for a minute or so and eliminate this higher TDS water. I like the convienience of having pressurized DI water on demand so I live with the shorter DI lifespan.

[shikhyung]

TDS creep comes from short cycles, so does it better that just leave the valve open, let it drip to the 55 gallons drum storage, till we turn off.

[AZDesertRat]

Yes, if you have the time to wait or can let it run overnight. One advantage of the pressure tank though is it makes a float valve work better with a positive shutoff, sometimes without the backpressure a float seeps or does not seat.

[shikhyung]

Understand now. Thanks AZ.