RO Water

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I guess it depends on what the TDS of your tap water is to begin with. The tap water at my house is around 450. When i test after the RO unit i read around 20-25 TDS which i wouldn't put in my tank, but when i test after the DI filter it reads 0. So i'm assuming if your TDS is low enough to start you may not need it.
 

Dihydrogen Monoxide

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Reverse osmosis water is water that is filtered mechanically. There are particles that are small enough to get through a RO membrane that are not desired/needed in reefs.

The key would be to test the TDS of the effluent water from the RO. From there decide if those 10 - 20 ppm TDS are enough to bother you ;)

DI additions can be exceptionally helpful and very inexpensive to maintain as the media can be "recharged".

I would highly recommend a De-ionizing chamber.

Here are some ions that will make it through a RO membrane and removed by a DI.
Phosphate, silicate, carbonate, Nitrate, Nitrite. Some old enemies of reefs.
 

Burks

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Phosphate, silicate, carbonate, Nitrate, Nitrite. Some old enemies of reefs.

A lot of the junk we fight to remove to begin with! Great post Mr. H2O (or HOH).

I screwed up and bought a RO unit that did not have a DI unit with it. Yeah, I can always buy a DI add-on ($35-$60) but I'd rather just save up for a brand new system with new filters, more stages, and a DI add-on ($150 or so).

My RO unit has served me well but it's time to upgrade.
 

Dihydrogen Monoxide

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Note that all of the Ions that I posted are not all bad, some are actually good! But more often than not we would like to control these ourselves rather than adding them inadvertantly.

Just thought I'd clarify :)
 

paintballer768

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Wow, thanks for the clarification H2O. My LFS only sells RO water. Its a lot better than the distilled water I used to top off with from CVS.
 

Dihydrogen Monoxide

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Personally I would say that distilled is going to be better than RO. But there are more factors involved than we can imagine!

The largest factor against distilled is if the company uses metal coils for the cooling as they may then be present in the water. Just be careful!

I recommend RO/DI over RO or Distilled, for aquaria needs.
 

Grace_O'Malley

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How do you test for the TDS? Is it from the RO/DI unit itself? Or is there some kit to test for it as well? We just installed a RO/DI unit and after the RO it was 9 and then after the DI part it reads... ZERO :biggrin:
Can that reading on the DI part be trusted? (This is a brand new unit) I guess I am a bit apprehensive as we have had some real problems with clearing up some Red slime algae in the tank, which was all before we got the RO/DI unit.
 
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paintballer768

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Personally I would say that distilled is going to be better than RO. But there are more factors involved than we can imagine!

The largest factor against distilled is if the company uses metal coils for the cooling as they may then be present in the water. Just be careful!

I recommend RO/DI over RO or Distilled, for aquaria needs.

I rather do RO water because the CVS distilled gave me a phosphate reading. I have no way to export those besides water changes, and its a real pain. But alls been well for me so far.
 

Dihydrogen Monoxide

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How do you test for the TDS? Is it from the RO/DI unit itself? Or is there some kit to test for it as well? We just installed a RO/DI unit and after the RO it was 9 and then after the DI part it reads... ZERO :biggrin:
Can that reading on the DI part be trusted? (This is a brand new unit) I guess I am a bit apprehensive as we have had some real problems with clearing up some Red slime algae in the tank, which was all before we got the RO/DI unit.

If you are using a TDS meter to measure the RO/DI water then I would say that the water can be trusted.

For Cyano Frequent smaller water changes that you siphon out the Cyano every time will get you slime free in no time ;)

Rinse frozen foods in pure water, and cut back on organic load in the aquarium, fresh GAC helps as well.
 
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