RO Water problem - white mossy growths

[apersaud]

I'd like to request advice on a problem with my acrylic RO Reservoir which is now getting chronic and recurring white mossy growths inside.

I use the RO Reservior to top up evaporated water from my reef tank. I have cleaned the RO unit as best I can and added a bit of vinegar to kep it disinfected. However the problem has recurred.

I will be replacing all the filters in my RO unit but haven't done this as yet.

Please see an attached picture that illustrates the problem I am expereincing.

I would appreciate any advice that anyone can provide.

Thank you - Avi

 

[dskidmore]

I assume your RO unit is the style that has the carbon cartridge before the RO membrane? (this is the most common type)

The most common RO membrane is sensitive to chlorine, so the chlorine is filtered out before the water goes through the membrane, and the resulting water is completely unprotected against microbes.

How long has it been since you changed your filter cartridges? This mossy stuff must be living off of some nutrients remaining in the water, unless there's nutrient rich dust falling in the open top.

This may sound crazy, but if it was me, I'd set up the reservoir as a freshwater planted aquarium. If plants and algae are competing for nutrients remaining in the water, then more harmful things won't get as much of a chance to grow. A less eccentric approach would be to sterilize the whole system, get new cartridges, and put a tight lid on the reservoir.

 

[apersaud]

Thanks dskidmore.

The main membrane is about 2 years old. I think the water supply might be "stressing" the RO unit. I will be changing the prefilters and membrane this week and sterilising the system.

The unit has a tight fitting lid on top. I'll try this before following up with some of your other ideas. Since I don't have too many of my own, I'm more than happy to consider any others - even if they are "eccentric".

Thanks

 

[dskidmore]

Oh yeah, at 2 years your membrane is probably toast and letting lots of nutrients through, feeding the white fuzz.