reverse osmosis deionization-cost of units-cost of operating

[cdwyer38]

I have two 90 gallon tanks, 1 reef and 1 freshwater. Just looking for advice on the commercially available ro/di units. How they work? How much does the water cost per gallon after considering filter cost? and anything else that will help me before I buy.

Thanks-Clark

 

[Robin Goodfellow]

hi.
The operating cost of RO is not sufficient, and mostly depends on your water cost. For RO only, the filters (prefilter, carbon, and RO membrane) will run you about 5 cent per gallon total. With the cost of water (waste 5 gallon of water for each gallon of RO), it is just pennies per gallon. DI is slightly more expensive, maybe about ten cent per gallon if you use RO water, but will be much cheaper if you recharge the resin yourself.

So for each gallon of RO, you should be paying less than 15 cents per gallon, and for RO-DI, it is less 25 cent per gallon.

 

[AuaFX]

You may want to look at a permeate pump, it cut the waste ratio by up to 80%.

 

[Robin Goodfellow]

...it cut the waste ratio by up to 80%.

hi.
The key words here are "up to." Permeate pump is efficient if it is used on a closed system (pressurized storage tank, etc.). But if the user is storing the water in a container opened to the air, it is useless.

 

[AquaFX]

True,

But well worth the savings.

http://www.aquariumwaterfilters.com/ROD ... ePump.html

Great if your going to have a drinking water kit, pressure tank is already there.

 

[djasper99]

True,

But well worth the savings.

http://www.aquariumwaterfilters.com/ROD ... ePump.html

Great if your going to have a drinking water kit, pressure tank is already there.

Interesting.

I was considering one of those combo systems that give RO drinking water, stored in a pressurized tank. You flip a switch to get RO/DI water for the reef. Would a permeate pump work with that? I assumed in RO/DI mode, the treated water was not going into the pressurized tank, as there is a separate tap for the reef water, and the drinking water comes out of a spigot installed in the sink. I hate to waste water.

 

[Robin Goodfellow]

hi.
The DI water will be from the RO tank, since the RO membrane can't keep up with your demand if you open the spigot all the way. So having a pressurized tank will enable you to get about 3 gallons (depends on the size) of RO/DI in matter of minutes. Without the tank, you will need to wait for hours.

The permeate pump will offset most of the disadvantage of the pressurized tank, namely, lowered efficient in producing RO. However, you have to consider the economics of the purchase. The amount of saving with the permeate pump may not justify the purchase price. It really depends on your amount of usage.

One good way to tell a good salesman from others is that a good one will ask you questions to determine rather you need the item, instead of giving recommendation solely based on the amount of commission when the credit card number is obtained.

 

[AquaFX]

There are different ways you can set up your RO/DI system with a permeate pump. You can have the water back feed from the pressurized tank and go through the DI if you like or you can keep the 4 gallon tank as a drinking water reserve, it is up to you.

The permeate pump should not lower the efficiency of your RO system. The non-electric pump changes differential pressure across the system, it is my believe (understanding) it increases system efficiency and stop TDS creep.

Also there are several benefits to this pump, one being economic. Then there is the ecological conservation of water. Then there is the elimination of TDS creep, which will tax your DI. So, yes, it is important to get someone who knows his or her stuff when you are shopping product.