RO/DI and TDS of 896
 

So after using tap water for a number of years I finally decided to buy an RO/DI unit. Got a pretty nice 6 stage 100gpd one. Also came with a TDS meter, thought well I'll test the house water here and see what we come up with. First test came up 896, odd, I thought 250-400 was normal....tested again came up 884. After running the first 40 gallons out and throwing it I made 20 more gallons and retested, thus far I have not gotten any readings under 23. Bought another TDS meter to verify it was not that, same readings. Should I expect any better?

The effluent from an RO/DI (or even a DI alone) ought to be 0-1 ppm TDS when not depleted.

What brand?

The high input TDS will lead to faster depletion, but should not make a good unit product poor water prior to DI depletion.

[url]http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120195002503[/url]

I guess I was just assuming that there is only so much it can do before its at its limits. With such a high initial reading perhaps I'll only ever see 23 or so.

No. That is true for RO only, but not the DI. :)

My municipal well water runs about 850 and my RO out is 6, DI out is 0, on a 4 stage 60gpd unit.
Bob

Unfortunately you bought a very low quality system, the price should have been an indicator, but you are not the first. With RO/DI you really do get what you pay for and its proven over and over. My tap water TDS is 835 and I get a RO only TDS or 5 to 6 and my DI is always 0. It takes high quality components to produce water like that but any of the reef quality systems found here on RC should get you in the RO only TDS range of 12-15 and DI of 0 or very close to it. Personally I would return that unit telling them you are not satisfied with its results and spend about $160 on a system that is proven to perform. I hate seeing reef hobbyists takne in by false advertising and bogus claims from some e-bay vendors. Its a bad thig but e-bay does not police vendors and their claims unlike those who sell in printed media or on TV or radio wher the Federal Trade Commission makes vendors live up to their claims.

Firsthesitation,
if you can return it go to the sponsor forum, The Filter Guys, or Buckeye, great products, great CS, and info, set you up with your needs and DI and filters 1/2 the price of the on line major suppliers. Sorry, I learnd too, the hard way, but I get 2 for the price of one from TFG's on DI cardrdges now.
Bob

If you are using the post filter drinking water filter, that can actually add TDS back to the water. For reef use remove the final carbon stage and measure right after the DI.

Hmmm, K thanks for your suggestions everybody, I've contacted the seller on eBay and I'll see what they have to say. Unfortunately I did not learn about the filter guys until after I already bought that unit. :( I guess now I really feel like a sucker.

Justdrew - I guess I did not know that about the drinking water stage. I'll take that off later and retest. I just figured it couldn't hurt to have the extra filtration.

With a TDs of 896 there really is only one RO/DI unit to consider and thats the Spectrapure MaxCap. No other unit on the market has a individually hand tested and guaranteed 98+% rejection rate RO membrane or custom blended DI resins designed for water such as that. It will outperform any other unit available guaranteed. Its what I ended up going with when a normal 75 GPD RO membrane would only get me down to about 15 TDS and DI only lasted 150 gallons per refill. I now get a RO only TDS of 5-6 and DI lasts a minimum of 630 gallons per cartridge for the MaxCap and the SilicaBuster has over 1900 gallons on the very first cartridge and its still at 0 TDS. My savings in DI alone has already paid for the difference in initial cost, not to mention I am getting much better final water quality.

Will have to look into that, initial cost of $350 is a bit steep for me......I spose if it works though.

On the other hand i guess i shouldn't complain about having a TDS lower than 40 since I was putting 896 PPM in my tank for the last 3 years......

Getting a used one is also an option. If you can find a reefer that is getting out of the hobby, they may have one for sale at a pretty decent price. I got mine for like $75 and get 0TDS out.

Take a look here, you can't beat this price for a Maxcap system.

[url]http://www.azseabottom.com/ROMAXCAP.html[/url]