RO DI unit

Its a low quality drinking water filter at best. They add a couple of little dinky hollow tubes with a little resin bobbing around in them and try to pass them off as reef systems but they are nowhere near the quality you will find from most RC sponsors/vendors.
Take a look at
www.thefilterguys.biz 75 GPD Ocean Reef+
www.buckeyefieldsupply.com 75 GPD Premium series
www.spectrapure.com 90 or 150 GPD MaxCap RO/DI
www.purelyh2o.com 75 GPD Optima series

All are much better reef quality quality units with true DI filters and high quality membranes and other filters.
 
Is there a way to tell if these Ebay units are sub-par? If TDS readings are 0 and PO4 is 0, what else do you test for?
 
They may or may not get 0 TDS after the DI stage. The piece that does the work though is the membrane and if they are not giving you 98% rejection with the RO only then they are sub par. Cheaper knock off membranes and lower quality ones are less efficient which in turn means shorter DI life which means greater cost to operate. Most of them use little 6oz, 12oz or in rare cases 16oz horizontal DI tubes where good quality units use vertical 24 oz canisters and cartridges that make full use of the DI inside them, horizontals short circuit and channel making poor use of the DI resin.
Cheaper units use very low quality prefilters and carbons which lead to short RO life since they are what protects the RO membrane. Good units use high quality prefilters and high quality 1 micron or smaller carbon blocks capable of adsorbing up to 20,000 gallons of chlorine and VOCs vs 200 to 300 gallons for most e-bay units.
There really is no comparison when it comes to water quality, long term cost of ownership and membrane life.
 
But if the unit you have is reading 0 TDS after the DI stage with a TDS meter and PO4 is also testing at 0, is the water as pure as it is going to get? Regardless of brand, would water with the above tests be considered optimum for a reef?
 
Yes, it will be as pure as it's going to get. The membranes and resin won't last as long with a cheap unit as with a better one, that's all.
 
Thats cool. I have been using a no-name unit for about 3yrs. I just wanted to make sure I was not missing something in my testing.
 
Re: RO DI unit

<a href=showthread.php?s=&postid=9314061#post9314061 target=_blank>Originally posted</a> by reefer4sho
http://cgi.ebay.com/AQUARIUM-2-110G...9QQihZ002QQcategoryZ20756QQrdZ1QQcmdZViewItem

I'm somewhat of an ebay whore and saw this, let me know what you guys think. Looks legit...
Click to expand...

There are a whole bunch of folks selling RO/Di filters on eBay. Some look to be dirt cheap while others are charging almost as much for shipping as the cost for the unit itself. Gee...like we're not going to notice that, huh? :)

Anyway, what this unit is hawking is a couple of 'non-standard' post filters. By that I mean the smaller element canisters are not as popular as the 2.5"x10" clear canisters, so the refills will probably cost more, or be harder to find.

As for the filtering elements themselves, it's not clear on what quality element you're going to get. And there is a world of difference between what all is being sold on eBay or the internet.

Most of the canisters making up these cheapie filters are standard issue stuff. Not much difference between the high-dollar units and the el cheapo units in that department. After all, how sophisticated does a canister have to be to hold a cartridge properly and not leak? Saying that, there are probably exceptions.

My advice: if you're a true-blue DIYer, go for it. Then once you get the hang of how it's supposed to really be, then you can fix it however you like. But if you're the kind of person that needs to have your hand held through every procedure, you're probably better off sticking with a reputable dealer.

Just make sure that the one you buy has a replaceable restrictor valve on it, so if you ever want to go with a different capacity membrane, then that won't be an issue. Some of these things have the restrictor molded into the canister and then you are stuck with whatever membrane size it's made for.

The other thing you need to make sure of is, that the unit has enough of the necessary accessories to shut itself off, once it makes and stores the amount of product water you desire. There are several ways to do this so be prepared. You don't want the thing to run all the time or have to constantly monitor it so it does not overflow whatever it's storing the product water in. Besides if it's allowed to run 24hr/day, that's just not very environmentally responsible, IMO. You are aware that these things do waste at least 4 times more water than they make, right?

So that's my spin on it all :spin3:
Guy
 
I am aware of how they work. The unit in the pic is from Filter Direct and although I don't have one of their units, I know they have been around for at least 4 years. Not much by some standards I guess.

I personally use an Aquasafe unit from Ebay and I bought replacement cartridges at the same time. I have yet to have buy anything new on the unit and it has been up an running for 3 years or more. I totally agree about being careful on Ebay but with my unit, I know it was cheaper than some of the name brand units the LFS sells and reads 0 TDS and no PO4. I just hate to see people steered away from something that can actually perform. Unless I am not testing for something, my water appears to be pure.

Maybe I have been lucky but I know a few forums of where people have used Aquasafe and filter direct units with great results.
 
Results are mixed at best. Tel us what you readings are. tap, RO only, and RO/DI. Those are the numbers that tell the whole story. Any unit should be able to produce 0 TDS at least for a little while but its how well it works over time that determines how good it is and how good of a deal it was. Talk to Randy Holmes Farley over in the Chemistry forum and ask him how long the membrane lasted in his Spectrapure unit. Its 10 years and that is a long time for a membrane to last in almost perfect condition. You won't get that with cheap replacement filters and you won't get 99+% rejection with a cheap membrane which is what makes the DI work so well and last so long.
 
I will check my source water and see what it is. I know I only have about $75 in the unit though. It was a lot cheaper at the time and has done well so far. I guess for longevity, we will have to see.
 
Showing a reading of 0 for phosphates doesn't necessarily mean anything. Test kits that we buy in this hobby WILL NOT detect orthophosphates (aka, organic phosphates), only inorganic phosphates. If you want to make sure that you have no phosphates, you're going to have to purchase a specialized test kit and the ones that will pick up on orthophosphates are $75 or more.
 
i have that unit, works fine for me, however my tap is 45 tds, would it work for someone that has 300 at tap? no idea, but b4 you shop for a unit , you should know your tap tds...........
 
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