Reef nutrition

BRS RODI

Reefers...what are your experiences with the RODI units sold by BRS? I live in SF and as much as I enjoy Manfred's company at Natural Life, I'm really tired of running to South SF every week and thinking of adding a unit and installing it on my back porch. Anyone running one outside? I know there's a ton of waste...should I go cheap with the 75 GPD, or splurge for the one that reduces waste?

Thanks
 
The extra splurge for me to get the 150gpd upgrade helped both the rate of production and reduces waste. The 75gpd RODI unit took me 2.5 hours to fill up 5 gallons, now I’m currently at 50 mins per 5 gallons. That alone was worth the upgrade for myself.


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Our club sponsor Air, Water & Ice makes units that are a really good value for the money. If you are looking to get your water as squeaky clean as humanly possible (low ionic things like Silica), the SpectraPure units are pretty much unparalleled. You'll pay for the difference, however.
 
So for the canisters, valves, and such, BRS/generic is fine.

For the membrane though, they are not the same.
DOW is something like 96% rejection.
Spectrapure was 99% I think.
Specs are on the web.
That difference affects how fast the DI is consumed.
It also affects water quality if you are slow to change DI (like me)
Does it matter ... to me it does.

Agree on waste water - answer to that is two membranes, not different brands.
And a booster pump, if you have low pressure.

Opinion: I worry about higher flow rates also. Rejection ratios, chloramine absorbtion in carbon, etc.
So perhaps 75 max.
 
Here is a very technically correct explanation of the numbers surrounding reverse osmosis: https://www.amtaorg.com/understanding-salt-passage-vs-salt-rejection-in-reverse-osmosis-systems
In layman's terms, whatever the membrane does not reject passes through it. It then falls to a later stage in the purification process to remove those things, either another membrane or your de-ionization stage. However, in general there is a trade-off here: higher rejection rate membranes typically operate at a higher pressure and generate more waste water than lower rejection rate membranes. So if you are going to run higher rejection rate membranes, the motivation to run two membranes is really high. Nearly all membranes are made by Dow Chemical, so 99% chance that whatever unit you buy is going to have a Dow membrane(s) in it. The remaining differences are mostly build quality and features.
 
I have a unit with two membranes, running 5g at a time and so far is close to 1:1 ratio
TDS out the membrane before DI ~1; zero after the DI

In the next weeks I'll be setting the 180gpd back online

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I have the brs 150/day with the water saver function. The water saver part has a valve to turn it on or off. When it’s off I would guess that I get about 1:4. I typically will run it this way at the beginning to flush out the tds creep and then switch it on so that I get closer to 1:1. I don’t worry so much about the waste water since I have it set up to run out to my front yard tree. It never gets watered otherwise.
 
I started with the BRS 75 GPD unit, and expanded it with the dual membrane water saver and a booster pump (apartment had low pressure). Its a solid system. I have it installed in a cabinet at the side of my house and it feeds into a pressure tank. Right now since I'm tankless it provides drinking water.

Honestly there isn't a lot of magic to the canisters that hold the filters. Cheap versus expensive there isn't a difference. The filters you should probably not cheap out on. I used to buy cheap filters off ebay but they didn't last as long as better quality ones like what BRS or other retailers for reefing sell.
 
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