Is it necessary to use 0 TDS water for top-off?

[clown99]

I have a dedicated RO/DI filter for mixing salt. Its output is 1TDS. And I have been using this water for top-off as well.
I also have another RO filter for drinking water which outputs 25 TDS. Living in CA, I want to reduce RO waste water (4gal of waste water for every 1gal of filtered water). So I switched to a Watts Premiere UF-3 system that filters out the bad stuffs down to 0.2um. I assume silicaThis has no waste water but it keeps all of the dissolved solids (TDS=290) and minerals, etc.
Is it ok use this for tank top-off?

 

[Jekyl]

Personally I don't even use the water when it's 1tds from having a filter lose effect. That's just me and my opinion though. Too many unknowns.

 

[Red_Beard]

depends on what you have in the tank. Fish only would probably be fine if you did a large water change every now and again. All of the dissolved solids WILL remain in your tank when it evaporates out, so whatever is in that water when it goes in will gradually climb higher and higher. Corals, SPS especially are very sensitive to this, but some of the other less picky coral would be fine if you did regular large water changes to remove whatever accumulates. Unless some of the TDS is copper... then maybe not.

At that point though you are wasting both salt AND water. Best bet would be just get a watersaver pack/ 2nd RO membrane and a booster pump.

 

[Jekyl]

As far a clean/waste water are you using a booster pump? It can reduce that ratio.

 

[Supa]

I got all new filters for my rodi unit (good filters too) and new DI resin. And it shows 1tds…. It’s never shown that before when using the cheaper filter…. I used the water and haven’t noticed any ill effects yet…. Guess you never really know what the 1tds exactly is unless you send off for a test or something but yea , just my recent experience ….

 

[Randy Holmes-Farley]

If you wouldn't use it to make new salt water, it's not usable for top off. Most people add more new water via top off than water changes.

"So I switched to a Watts Premiere UF-3 system that filters out the bad stuffs down to 0.2um. I assume silicaThis has no waste water but it keeps all of the dissolved solids (TDS=290) and minerals, etc.
Is it ok use this for tank top-off?"

A particulate filter doesn't remove ANY dissolved solids. That's the very definition of a dissolved solid, and all the bad stuff like copper, silicate, ammonia, etc. would get through.

 

[aquaman67]

Are you on “city water”?

Some municipal water systems use a form of phosphate to treat the water. Phosphate is something that can pass through an RO membrane.
That’s the whole point of DI. To remove what passes through the RO by ionic charge.
You could be potentially pouring phosphate into your tank every top off.

 

[clown99]

I'm on city water. So in conclusion, DO NOT use non-RO/DI water for top-off. Thanks for the advices.

 

[zheka757]

im on well water, here in Florida, water comes out from ground at 700-1200dts, then i have whole house ro system water comes out at 70-90tds after house RO. then I have RO just for the tank and water come out at 2-4tds this water goes strait to my top off. i did CP test on RO water. and there was noting that would cause me problems to my tank at 2-4tds. my point is as long as you know what's in that water, as long as its nothing harmful, why not use it?

 

[Randy Holmes-Farley]

im on well water, here in Florida, water comes out from ground at 700-1200dts, then i have whole house ro system water comes out at 70-90tds after house RO. then I have RO just for the tank and water come out at 2-4tds this water goes strait to my top off. i did CP test on RO water. and there was noting that would cause me problems to my tank at 2-4tds. my point is as long as you know what's in that water, as long as its nothing harmful, why not use it?

That's certainly a reasonable point. There's nothing wrong with TDS. It's what comprises the TDS that matters. If there is not significant copper (from your pipes), ammonia, or other undesirables, it is likely fine (as long as it stays that way).

OTOH, when the TDS going to a DI is only 2-4 ppm, a DI lasts a long time.

 

[zheka757]

That's certainly a reasonable point. There's nothing wrong with TDS. It's what comprises the TDS that matters. If there is not significant copper (from your pipes), ammonia, or other undesirables, it is likely fine (as long as it stays that way).

OTOH, when the TDS going to a DI is only 2-4 ppm, a DI lasts a long time.

Lol, I actually did use di filter for first couple years, it only last me like 3-4 month. I just got tired of replacing di filters, and after cp test on ro water, I was ok with leaving it as is.

 

[jmichaelh7]

if your running sps i would run 0 tds top off water

like others mentioned if its fish only, i dont know i would still run 0 tds. last time i ran 5 tds-10 tds bryopsis came!