~simple RO DI question~

[italia]

I'm looking into getting an RO DI unit but so many out there to purchase, not sure is the best brand. How many stages should it have. seen some with 3 stage while others have 7 stage with UV all the bells and whistles.
I just want clean pure water, don't need to make alot, maybe 30-40gpd would be nice. anything more would be better for the future if and when I upgrade the tank and need more water.

anyway, lookin on ebay alot to find one so if anyone can recommend a particual one on ebay, I'd greatly appreciate.

 

[ellisz]

personally, I would check with some vendors on this site. The ones on ebay will work but will need work later most likely.

airwaterice.com
bulkreefsupply.com
buckeyefieldsupply.com
thefilterguys.biz

I am sure there are others ...

Check there prices and their product and the compare that to ebay.

 

[italia]

so still the question I'm wondeing is whats the additional benefit of a 7stage vs a 3 stage? will the 3 stage pull a lower final TDS reading then a 7 stage or will they all result in the same TDS final reading?
trying to stay as cheap as possble but want what is necessary.
thanx

 

[9501gle]

I have a 5 stage and get 1 TDS when I put in new filters.

 

[ellisz]

Depending on your local water, you may only need a sediment filter and a carbon block with the RO membrane and the DI filter. I think a 5 stage is the most common you though. Any type of filter after the DI stage is not needed for reefkeeping.

The RO membrane and the DI filter are what get you the low TDS. The other filters just get the water ready for the membrane so it is not damaged.

 

[AZDesertRat]

You question was which is best, that is undisputably Spectrapure without question. No other vendor individually hand tests their membranes and guarantees their efficiency in writing. Also no other vendor hand blends every ounce of DI resin that leaves their facility so it is the absolute best it can be for specific water conditions.
As to the number of stages, do not get hung up on this as it is a sales gimmic by most vendors. The answer is you need 3 stages for RO and 4 stages for a good RO/DI, that's it no more. The idea of two carbons goes back years and years when carbon was not as effcient as it is today, one is all you need and its all the better manufacturers and vendors supply.
If you want better treatment you are much better served by dual DI not dual carbons.
The key thing is what the stages contain, buy the very best you can afford and it will reward you in the end with greatly extended RO membrane life, DI life and exceptional water quality. Do not skimp on RO/DI as water is the single largest ingredient in a reef system and everything in it depends on that water quality.

 

[reef_doug]

I would look into the Spectrapure MaxCap at $349. I bought a Kent unit many years ago and from what I've learned since then, you can't beat the "value" as defined in long term water quality output from the Spectrapure MaxCap. Their handselected membrane is the heart of the system, protect it well with good prefilters and it will perform well. The Maxcap DI will polish the output to 0 TDS.