Water filtration Questions?

[chopsuey]

I have always used RO/DI water for my tank. Lately the cost of this water from LFS has increased so much that it is no longer practical to purchase. I have found a place that sells RO water that is filter with a carbon and a 00.5 micron pre-filer; also it goes through 2 UV chambers. But it is not Deionized.

My question is: Is DI very important?

I mean you see water filters that do not have the DI option for sell by all the major manufactures of marine equipment.

The obvious answer is RO/DI is better than RO. but is DI absolutely necessary?

 

[AZDesertRat]

A TDS meter will answer your question. If the source water is pretty good to begin with and they are getting 98% efficiency from their RO then it may be OK but not knowing the numbers its hard to say. It would certainly be better than tap though if thats your other choice.

 

[chopsuey]

LOL tap would never be an option.

I am just curious. I have a Kent 30GPD HI-S RO/DI unit but over the years the membrane is burt out. A new one would cost me about 90.00 and of course the cost of making the water my self.

Thats why I have reverted to getting it from my LFS. Up until recently the price was fair. The last time I got water from them the price trippled. So I was just wonding how important the DI really is.

Is TDS the end all be all? Or are there other impurities that TDS does not test for that are removed from DIonizing? What does DIonizing really do and is it very important?

Kent sells the same RO system I have with out the DI filter so I was wondering if I could get away without the DI process or is there something in the water that needs to be removed by DIonizing?

What are the consequences for not using DI water long and short term?

Has anyone had great sucess with out DI water?

 

[AZDesertRat]

You should be able to get a new 98% rejection 75 GPD Dow membrane and a complete add on DI kit for less than $90. That would give you much faster production and better water. If you don't want to add the DI kit ($38) get a Spectrapure SpectraSelect hand tested guaranteed 98+% 90GPD membrane for around the $90 and get the best possible RO water you can without DI.
Again without knowing the tap TDS in your area and the efficiency of the RO membrane its just guessing. A TDS meter is needed to tell you anything. There are contaminants that the RO membrane by itself is not good at just as there are things DI is not good at. It really takes the complete package, carbon, RO and DI for best treatment.

 

[chopsuey]

Where can you find the 75GPD membrane and DI kit for less than 90.00? Heres a link to the membrane that I currently have in my RO/DI system right now. I just need a new membrane as all other filters were recently replaced.

http://www.marinedepot.com/md_viewItem.asp?idproduct=KM2241

If you can find one on another site for cheaper please share. My LFS sells them for $99.99 and thats about what it will cost from Marine Depot after shipping.

 

[AZDesertRat]

www.thefilterguys.biz $36 for the DI kit, $45 for the membrane and $6 for a matched flow restrictor.
www.buckeyefieldsupply.com
www.purelyh2o.com
www.spectrapure.com

All are Reef Central sponsors and some even support group buys or otherwise give discounts to RC members, ask them about their specials.

 

[chopsuey]

WOW

Thanks AZDesertRat If the fiterguys 100GPD membrane will fit my Kent HI-s RO/DI I will be buying it 45.00 is a great buy.]

Thanks again for all your help.

 

[AZDesertRat]

DO NOT get the 100 GPD. It is not a true RO membrane but is a 90% rejection rate nano filter. Get the 98% rejection rate 75 GPD RO membrane as it will greatly extend the life of your DI resin. A very accurate rule of thumb is for every 2% you increase the efficiency of your RO membrane you double the life of your DI resin. This is very important and will save you lots of money on replacement DI resin over time.

 

[chopsuey]

Thanks again AZDesertRat

I ordered the 75GPD from purelyh2o.com

http://www.purelyh2o.com/product.php?productid=16190&cat=0&page=1

I hope this will fit in my Kent HI-S RO/DI housing. They all seem to be pretty standard.

 

[AZDesertRat]

It will fit perfectly. They are an industry standard size. Did you get the matched flow restrictor with it?

 

[chopsuey]

NO I didnt should I have??

I have never had one on my Kent RO/DI if is necessary I will order it as well.

Im assuming it keeps the incomming water pressure down to the correct pressure for the membrane? But does it conserve on waste water by restricting the flow going to the membrane or does it just save on the overall life of the membrane?

 

[DarG]

IT goes on the waste line of the ro canister and is necessary for the particular membrane, in your case 75GPD Filmtek to work like it should. I believe it provides the appropriate back pressure the membrane needs to work right. Anyway, if your system doesnt have an inline flow restrictor, then it is probably located on the waste port of your RO housing as a plug type fitting. You will need to remove that one (just pull it out) and install the 75 GPD one inline with the RO's waste tube.

 

[AZDesertRat]

Kent like Spectrapure may use a capillary tube type flow restrictor. Unhook the waste line and look inside it, you should see a small spaghetti sized tube stuck inside the 1/4" tubing. It may be able to be trimmed to the correct length for a 75 GPD but I am not sure. If not add a new one to your order.