RODI confusion

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ThatNewFishGuy

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May 4, 2010
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I have a 50 gpd coral life pur flo 2 RODI unit that I have been using for the past 2 years. I recently just picked up a 75 gpd RODI unit from a local reefer because he was selling it cheap and it came with alot of things that my unit didn't have(built in tds, flush kit, float valve setup with extra water storage.

What is the difference between a 50 gpd unit and 75 gpd unit. Is it just the amount of gallons of RODI water you can produce in 24 hours? I've read that in higher GPD systems, the water has less contact time with some of the stages and is thus slightly less pure than lower GPD systems.

My plan was to just take the goodies off the 75 gph and put them on my current unit but then I thought, wait a sec maybe 75 gph is better. I'm not sure though.
 

greech

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May 13, 2009
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They won't be any differnce in the water quality produced by a properly functioning 50 gpd and a 75 gpd unit. The 75 gpd will just make water 50% faster.

Russ
Yep and how that happens has to do with the membrane. The 75 gpd should have a slightly larger memebrane or multiple membranes.
 

Narwhal72

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Aug 13, 2009
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The larger RO unit will have more windings around the membrane (more surface area for water to pass through means more water flow). It will also have a different flow restrictor which will maintain the higher pressure at the higher water flow.

Andy
 

ThatNewFishGuy

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May 4, 2010
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I see. In that case I guess ill start using the 75 gpd unit. Well i guess I should check the price difference in membranes first...also, what and where is the flow restrictor piece that I hear a lot of talk about

Also is there any difference in qaulity amongst different brands of RODI unit? It seems like they are all made out pretty much the same plastic casings and airline tubing. I guess qaulity really depends on what filters and membrane u use, right?

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BuckeyeFldSup

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Jul 29, 2008
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The flow restrictor is somewhere on or in the waste water tube. If you want to give us a call when you are in front of your system I can walk you through finding it. Can also email you a set of instructions for installing a new one if you'd like.

There absolutely IS a difference in quality among brands. If you're new to these systems however you'll say exactly what you wrote above - "they all look alike to me." Not only is the difference in the filters themselves, but also in the housings, fittings, tubing, clips, instructions, service, and on and on. These systems are something you'll have for years and years - and a $5 or $10 difference in price, which is what a lot of beginners select upon, becomes meaningless.

Russ
513-312-2343
 

TL1000RSquid

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Apr 6, 2011
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50-100gpd membranes and restrictors are all priced quite similarly. Roughly $40ish for membranes and under $10 for restrictors.

Huge quality differences between different brands/sellers, I scored a new in box unit on craigslist dirt cheap made/sold by purewaterclub, by the time i replaced all the fittings and hosing that leaked it wasnt much cheaper then a unit from any quality legit seller.

BRS and BFS are both top notch places to get replacement filters or other parts.
 

ThatNewFishGuy

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May 4, 2010
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I appreciate that Russ, I think I found out it though. Only thing I'm confused about is that it doesn't seem to be wired onto the waste line. Instead it's wired after the membrane and before the ASO valve(which leads to the DI resin)...

Jlennon that definitely helps. I'm pretty sure the unit I got is one of BRS's older versions. It doesn't look like the model they have in there newer youtube videos. However, it does have the push to connect murlock fittings which BRS is so fond of. I think polyethelene tubing was switched around cause its different colors and the wiring is kind of confusing to me...it seems like the flush kit is wired onto the waste line. I thought the flush kit was supposed to be wired before the membrane so that it could increase the amount of water flowing over the membrane. Why would it be wired into the waste???

Another thing I noticed from watching the BRS vid on the auto top off kit and looking at that diagram above is that I dont have a check valve wired in after membrane and before the ASO valve. Is this necessary for the functioning of the auto top off?

Here's some pics:





 
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