RO unit

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Fishfood
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RO unit

Post by Fishfood » Wed Aug 03, 2011 1:59 pm

So its been a while since I changed my filters and membrane on my kent hi-s 35gpd RO/DI. I actually turned it into a 4 stage unit after talking to Andrew about it a few yrs ago. My question is mainly about the membrane. BRS doesn't have a membrane for this unit. They have other gpd units lists as well as flow restrictors. I really don't know the flow going through my unit. I have great water presure though. If I want to put in say a 75 gpd membrane what would I have to change on this unit. The normal replacements for what I have are $90. Those 75gpd membranes are $30.

Without changing anything do i have my RO/DI set up properly with it just attached to washing machine line with nothing else but the additional canister. If I change membranes what other changed do I need to do?

Andrew....

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Re: RO unit

Post by Amphiprion » Wed Aug 03, 2011 7:10 pm

Other than a flow restrictor and (edit: matching) membrane specified to the desired output, there's nothing that is necessary to change. Unless you have a very specialized unit, all housings and canisters should be standardized, so that shouldn't present a problem. 75 gpd is pretty much the most cost-effective route in the long run in practically all regards, which is the main reason I went with that volume. Oddly enough, the 75 gpd membranes also feature the highest rejection percentages, with a minimum of 98%. There are also several places to purchase high silicate/phosphate adsorptive resins, if you still would like high silicate rejection. Shoot for the non color-changing varieties of any resin, if possible, since they have higher scouring capacities.
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Re: RO unit

Post by Fishfood » Wed Aug 03, 2011 8:10 pm

So this is what I have: http://c3.f3images.com/IMD/UserManuals/KM1491.pdf

What would be the difference between the HiS membrane and this membrane: http://www.bulkreefsupply.com/store/pro ... brane.html

I have the Nuclear Grade DI Resin, 5 micron sediment filter and then a 5 and 1 micron carbon block I believe.

so anyway if i went with the 75gpd membrane Id just need to take the flow restrictor out of the flush kit and put a 75gal flow restrictor on the output wastewater line. I guess I'm trying to figure out what I'm losing if i go to the 75 from the 35 other than less money.

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Re: RO unit

Post by Amphiprion » Wed Aug 03, 2011 8:44 pm

You won't be losing anything, other than higher slilcate/phosphate rejection at the membrane stage. Not particularly a problem in most cases, though if that is a concern, a resin with high silicate affinity is a far cheaper alternative and is quite effective.

The unit appears to have all standard fittings, etc., so you should be fine.
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Re: RO unit

Post by Fishfood » Wed Aug 03, 2011 9:04 pm

but I would have to take the flow restrictor out that came with the unit and install one for a 75gpd one right? I'm assuming the one they include is for the 35gpd membrane.

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Re: RO unit

Post by Amphiprion » Wed Aug 03, 2011 9:21 pm

Yes, otherwise it would not only yield very little water, but it will wreak havoc on the membrane's efficiency, since it is very dependent upon water pressure. You'd probably get in the low 90% range without a new flow restrictor.
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Re: RO unit

Post by Fishfood » Wed Aug 03, 2011 9:56 pm

well it looks like I'll be putting in a brs order in the next month. If anyone wants to get in on it let me know. It will probably be near the end of august.

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