RO too fast

[Vince1961]

RO system (with sediment and carbon prefilters) is rated for 24 GPD and actually operared at that rate for a half a year or so, with a waste rate around 70-80%, but recently started producing 2-3 times as much at about half the waste rate. Pre-filters changed. Filters and membranes are properly seated. It's still producing 50-75 GPD at 50-60% waste rate.

What gives?

 

[bpattengale]

I've used a smaller system like this for water production on my saltwater tank. I assume this is something similar. In my experience this is a sign that the membrane has reached the end of it's useful life. Have you checked the RO water quality? My guess is that the quality has dropped. Second how much water have you put through the system?

 

[bimr]

Would suspect that you have an internal membrane failure. Check the water quality.

 

[Vince1961]

Yes it is for a saltwater squarium. I suspect water quality has fallen off a bit, but can't really tell for various reasons that would take too long to explain and probably are not relevant. Suffice it to say that I have no means by which to test other than taste, smell and diatom blooms.

The RO membrane is 11 months old. The package says to replace every 2-3 years or 10,000 gallons. I've done less than 2,000 gallons. I do have an unopened replacement membrane handy, but was hoping not to use it so soon. (Then again, I just read that RO membranes do have a shelf life. I got my replacement membrane about 5 months ago.)

 

[bpattengale]

The life of the membrane is also affected by the quality of the imput water. If your tap water has a lot of disolved minerals in it it is going to shorten the life span of the membrane. As bimr suggests the membrane may have failed. You might want to buy a reverse flow kit for your RO system as this can help prolong the life of the membrane. Also the membrane depending on the type can be degraded by clorine. I'd say replace the carbon and sediment prefilters along with the membrane. The carbon and sediment prefilters are going to need to be change probably every three months or more often depending on how much production you're using he system for.

 

[bimr]

bpattengale hsa made some good comments.

I would add that the shelf life is not important for this application. You should also be sure to get a good quality sediment filter. Perhaps a prefilter of using 5 Micron polyspun cartridge and a final filter with 0.5 Micron rating.