RO/DI and Temp

[Kasey]

I assume low temperatures are an issue for RO systems, as I have seen warranty disclaimers with regards to low temps.

What is the lowest temp for a system and does performance suffer the lower it is?

 

[Anonymous]

The lower the temperature, the higher the rejection rate, so if your metric for performance is purity, it actually goes up. The main issue is that the RO will have a lower yield, and a lot more waste water.

 

[Kasey]

Would a permeate pump be best then with colder temps?

 

[Anonymous]

No. Permeate pump only work if the output from the RO is against a pressure, such as a storage tank (bladder tank). It does not increase the output of your RO if you just drip the output into an open container.

Some loops the RO input in a big bucket of water to warm it up a little. It is particular an issue in colder climate where the water temperature is near the 40F to 50F. Some heat the water with a heater, but IMHO, it is a complete waste of electricity.

 

[Kasey]

Yes, I was going to use a bladder tank.

These are the "key features" listed on a permeate pump web page:
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# For membranes rated from 10 to 120 GPD using standard 1/4â€

 

[Anonymous]

I think there are missing words there. :wink:

# Saves up to 400% of waste water vs. conventional units

It is not a miracle pump, obvious. You need to consider how much water saving it is going to give you over the life of the pump. For people who use RO for drinking and cook, it is worthwhile due to the volume of water used. For most reef keeper, it may not work that well if you don't use the water that much.

If the RO filter is in a relative warm room, some people just use a long coil of PE tubing and run it thru around inside a tub of water.

 

[das75]

Used to run a coil of line in my sump before going to ro/di.

Need to balance off the gain in temp against pressure loss.

 

[stubbsz]

I think there are missing words there. :wink:

# Saves up to 400% of waste water vs. conventional units

It is not a miracle pump, obvious. You need to consider how much water saving it is going to give you over the life of the pump. For people who use RO for drinking and cook, it is worthwhile due to the volume of water used. For most reef keeper, it may not work that well if you don't use the water that much.

If the RO filter is in a relative warm room, some people just use a long coil of PE tubing and run it thru around inside a tub of water.

Yeah, the key thing is that they are great if you are filling a tank... you get more in the tank and as the tank fills to the brim, you don't waste a ton of water. However, if you don't have a tank, don't use a permeate pump. I use one because the RO water (pre my DI filter) goes to a tank for drinking water.

 

[Kasey]

Thanks for all the input gang.

I bought the 100gpd RO/DI from pure water club, with two outputs and a 4 gallon tank. Also bought a TDS meter and the permeate pump. Plan on using for reef and drinking.

I was thinking of connecting my inlet to my washing machine cold side.

My apartment (house) has no basement, just a poorly insulated crawl space. I'll have to take a small sample and stick a thermometer in it tomorrow, but the water is in deed cold.

What then, i guess, is too cold or too hot for good operation of an ro?

 

[Anonymous]

Depends on the membrane, but my guess is that anywhere between 50-70F is good range.

 

[brandonberry]

Here's what I use to heat my water line before it goes to my RO. I keep the temp set to room temp, so the heater only runs when cold water is flowing through it. The air line was added later because the water was stratifying and not warming the line enough.