Low PSI on new RO/DI filter

gideon2086 · Feb 4, 2020

I've been buying my water from the LFS for the past year, but after a recent tank upgrade (Red Sea 350) I decided the investment in a RO/DI filter was worthwhile. I purchased the advanced model from Marine Depot that claims to output 100g/day. When I test the pressure on my hose faucet I get a reading of about 55-60 PSI. When I have the RO/DI up and running the pressure gauge on the actual unit reads 20 PSI. Because of this I'm outputting only about 1.5 gallons an hour... which makes this equipment basically useless. Any thoughts out there?

Acroalan · Feb 4, 2020

You can find booster pumps available that will bump your pressure up and increase your RO/DI output and reduce waste water. I've seen them on Bulk Reef, but imagine Marine Depot carries them as well.

gideon2086 · Feb 4, 2020

Acroalan said:
You can find booster pumps available that will bump your pressure up and increase your RO/DI output and reduce waste water. I've seen them on Bulk Reef, but imagine Marine Depot carries them as well.

Thanks, just pulled it up... that's another $120+!

Is it normal for the RO/DI unit to pull only half of the PSI of the naked output?

Potatohead · Feb 4, 2020

No, something is off. Try taking the filters out (not the membrane) and flipping them around, or repositioning them or something. You should only lose 2-3 psi across the sediment and carbon filters.

gideon2086 · Feb 4, 2020

Potatohead said:
No, something is off. Try taking the filters out (not the membrane) and flipping them around, or repositioning them or something. You should only lose 2-3 psi across the sediment and carbon filters.

Ok, thanks. I'll give it a go tomorrow.

Potatohead · Feb 4, 2020

gideon2086 said:
Ok, thanks. I'll give it a go tomorrow.

Also make sure the flow restrictor is installed correctly on the waste line.

gideon2086 · Feb 4, 2020

Potatohead said:
Also make sure the flow restrictor is installed correctly on the waste line.

It came preinstalled... seems to be normal.

John08007 · Feb 4, 2020

That was my thought, flow restrictor wrong. Does the restrictor have markings on it? It needs to be matched to the gpd of your membrane. Maybe they gave wrong one

gideon2086 · Feb 4, 2020

John08007 said:
That was my thought, flow restrictor wrong. Does the restrictor have markings on it? It needs to be matched to the gpd of your membrane. Maybe they gave wrong one

It doesn't. This is the unit:

4 Stage Value Plus 100GPD RO/DI System

Makes up to 100 Gallons of RODI Water Per Day! BRS 4 Stage Systems are perfect for reefers who have water treated with chlorine or relatively clean well water. Self-contained on a single bracket making them ideal for tight spaces or where a non-permanent connection may be required. Every BRS...

www.marinedepot.com

Potatohead · Feb 4, 2020

It looks like a re-badged AquaFX unit, which I have. The flow restrictor is actually inside the waste line where it connects to the fitting.

I've had mine about three years, and coincidentally, I had a very similar problem. It took switching out the carbon block to correct it. I wonder if they had a bad run of carbon blocks and you just happen to have a similar problem. Weird.

S2G · Feb 4, 2020

You have a bad filter cartridge in there somewhere. Wheres the 20psi measured at?

wcharon · Feb 4, 2020

Can someone explain me the real function of the Flow Restrictor? I ask because i have a Kent Marine Maxxima Hi-S 60gpd and recently i changed all the filters, flow restrictor and installed a new Booster. I ordered the 30 -50 gpd restrictor and it reduced dramatically the waste water and also the product water. I found weird that the new one is yellow while the old one was blue.

I replaced the 30 with a 75gpd and now the waste water increased so i have to deduct that it is a combination of the new Booster and the restrictor. Will be testing the product water rate tomorrow but wherever i read it says to match the restrictor gpd with the Membrane GPD.

So which one will be ideally between the 30 and the 75 which is more GPD of the Membrane?

Thanks in advance.

John08007 · Feb 4, 2020

wcharon said:
Can someone explain me the real function of the Flow Restrictor? I ask because i have a Kent Marine Maxxima Hi-S 60gpd and recently i changed all the filters, flow restrictor and installed a new Booster. I ordered the 30 -50 gpd restrictor and it reduced dramatically the waste water and also the product water. I found weird that the new one is yellow while the old one was blue.

I replaced the 30 with a 75gpd and now the waste water increased so i have to deduct that it is a combination of the new Booster and the restrictor. Will be testing the product water rate tomorrow but wherever i read it says to match the restrictor gpd with the Membrane GPD.

So which one will be ideally between the 30 and the 75 which is more GPD of the Membrane?

Thanks in advance.

I believe since the water will take the path of least resistance without it all of the water will come out the waste line. You add the restrictor to force water to go through the ro membrane. Ive seen the small restrictors that go inside the line. Personally, id replace it with an inline then you can add a membrane flush kit to help your membrane last longer

wcharon · Feb 5, 2020

John08007 said:
I believe since the water will take the path of least resistance without it all of the water will come out the waste line. You add the restrictor to force water to go through the ro membrane. Ive seen the small restrictors that go inside the line. Personally, id replace it with an inline then you can add a membrane flush kit to help your membrane last longer

Thanks for the feedback. Yes they are inline restrictors on the waste line.

Potatohead · Feb 5, 2020

Any updates?

gideon2086 · Feb 5, 2020

Potatohead said:
Any updates?

Apparently the flow restrictor goes against the laws of conventional plumbing... when it is parallel with the lines it is CLOSED.. perpendicular is OPEN... this was my problem... good lord - carry on!

Nano427 · Feb 5, 2020

gideon2086 said:
Apparently the flow restrictor goes against the laws of conventional plumbing... when it is parallel with the lines it is CLOSED.. perpendicular is OPEN... this was my problem... good lord - carry on!

My guess would have been the flush valve is open. You‘d see a pretty high pressure and volume coming from the waste line, and very little water from product line. Once you close the flush valve the psi of the system would increase to almost the same pressure as the source water. You‘ll then see much more product water and much less waste. But it sounds like you have it figured out now.

theMeat · Feb 6, 2020

gideon2086 said:
Apparently the flow restrictor goes against the laws of conventional plumbing... when it is parallel with the lines it is CLOSED.. perpendicular is OPEN... this was my problem... good lord - carry on!

Actually if you have flush valve/flow restrictor ... when parallel with valve it by passed flow restrictor and is in flush mode.
Glad you figured it out. With 50-55 psi you should use a max of 75 gpd to have a long lived trouble free unit. For 100 gpd you should be upwards of 60 psi.
Is this Gideon from Valley Stream?

gideon2086 · Feb 6, 2020

theMeat said:
Actually if you have flush valve/flow restrictor ... when parallel with valve it by passed flow restrictor and is in flush mode.
Glad you figured it out. With 50-55 psi you should use a max of 75 gpd to have a long lived trouble free unit. For 100 gpd you should be upwards of 60 psi.
Is this Gideon from Valley Stream?

It depends... are you rich and is this Gideon a potential heir?

theMeat · Feb 6, 2020

gideon2086 said:
It depends... are you rich and is this Gideon a potential heir?

Lol
I’m not loaded with bread, or nearly dead.
Some things never change. Last time I saw you you were having rodi frustration.
If you were getting water from manny would expect your tds to be up there. Hope you checked it.