polyphosphate for residential reverse osmosis

[redhand]

I have hard water at home and found a company that sells small cartridges (2" x 10" in size)containing polyphosphates. I am hoping to use the cartridge before a residential RO system to treat the water. The RO system is small and meant for drinking water only (not a full home unit). The RO unit only uses small amounts of water (approx 0.5 gallon per hour of water). Any idea if this will work? I ran a RO system before but it only lasted a month or two due to heavy scale build-up.

 

[GarySCWSVI]

I don't think that will correct your problem. It may, in fact, cause additional scale accumulation. You should first ask the RO system supplier. Instead of feeding polyphosphate a better solution is to soften the water. If the hard water is scaling an RO membrane that fast you should also find lots of other soft water benefits in your home.

Gary Schreiber, CWS VI
The Purolite Co.

 

[kenvlach]

Agree with Gary that water softening will work and may benefit by preventing water lines from scaling up (especially the hot water).

I would be surprised if the system manufacturer doesn’t have instructions for dealing with such a common problem. Possible steps:
Descale with something relatively harmless like vinegar.
Increase the reject water ratio, so that dissolved solids don’t increase as much.

 

[redhand]

Thanks guys but I don't own my residence I rent. The landlord doesn't seem to keen on getting us a water softener. I need to treat only the water going into the RO unit.

 

[luissabate]

"The landlord doesn't seem to keen on getting us a water softener. I need to treat only the water going into the RO unit."

Have you tried to increase the reject? "Increase the reject water ratio, so that dissolved solids don’t increase as much" as kenvlach said.

No investment is required,(but you had to increase water inflow to get the same output, as reject increases).

If reject is very small, the RO cartridge will soon collapse. If reject is very large (more wastewater), the water may not have the required quality.

As rate is small: "The RO unit only uses small amounts of water (approx 0.5 gallon per hour of water)"; them it seems you will not have problems to increase reject.

Try something like this:
In: 0.7
Out: 0.5
Reject: 0.2

 

[kenvlach]

Also, check that the reject line is installed correctly and not clogged. Must be some reason for premature cloggging with such little use.

Again, check the owner's manual first, but perhaps you can disconnect the lines and backflush the system through the reject line. Consider descaling in the same fashion using vinegar.

Let us know how things turn out.
Ken