Watermaker Membrane Cleaning Chemicals

[Mikado]

Hello CF,

I recently installed a new Dow Filmtec membrane and was getting good flow and product water under 200 ppm TDS. I messed up and didn't pickle the system before I left the boat for 5 weeks. Now I still get product at under 200 but hardly any flow.

I have heard that you can clean the membranes with some level of improvement.

Does anyone have any suggestions on what and where I can purchase the acid and base cleaning chemicals to flush the membrane?

Thanks, Jeff

[ericoh88]

try



Ships Store


I boughts several items from Rich and he is very helpful on email support.



Have you tried running the unit without any pressure with both pumps running for an hour ? Hopefully this can clear the blockage.



Eric

[Mikado]

Eric,

Thanks for the advice. I’ll reach out to Rich and try running the system longer to see if flow increases.

Jeff

[billknny]

If you go to Dow FilmTec's website there are many resources there for how to care and clean your membranes.

[Paul L]

Have you measured the brine discharge flow? Make sure you are getting full flow there before you start with chemicals.

[David B]

Originally Posted by Mikado

Hello CF,

I recently installed a new Dow Filmtec membrane and was getting good flow and product water under 200 ppm TDS. I messed up and didn't pickle the system before I left the boat for 5 weeks. Now I still get product at under 200 but hardly any flow.

I have heard that you can clean the membranes with some level of improvement.

Does anyone have any suggestions on what and where I can purchase the acid and base cleaning chemicals to flush the membrane?

Thanks, Jeff

Five weeks is not a period I would consider pickling. Normally only done when you are leaving at the end of a season. It could well be just build-up in your pre-filter(s). Pull out the cartridge(s) and see what they are like. Give them a wash on the outside with a hose, then flush down the core with the hose to effectively back-wash them, and see how you go when they are re-installed (let then drain dry before re-installing to minimise the chlorine exposure to the membrane).
Also check the strainer on your water inlet at the hull fitting.

As for pickling, sodium metabisulphite is the one many manufacturers supply, and you can source it for a lot less than buying a 'pickling kit', but check first regarding your specific membrane.

[billknny]

Originally Posted by David B

As for pickling, sodium metabisulphite is the one many manufacturers supply, and you can source it for a lot less than buying a 'pickling kit', but check first regarding your specific membrane.

Be careful what you are recommending. The metabisulphite is a good pickling agent for the Filmtec membranes, but it is NOT compatible with all plastic parts, and the manufacturer of the entire system needs to have the final word there.

Spectra pumps for example, are not compatible with that solution, The generated acid damages the plastic parts in the Clark Pump. I believe they use a borate based pickle solution.

If the system was left for 5 weeks in warm temperatures with salt water on brine side of the membranes, it is very possible that cleaning will not be able to restore them. Too much biofilm will have accumulated.

[David B]

Originally Posted by billknny

Be careful what you are recommending. The metabisulphite is a good pickling agent for the Filmtec membranes, but it is NOT compatible with all plastic parts, and the manufacturer of the entire system needs to have the final word there.

Spectra pumps for example, are not compatible with that solution, The generated acid damages the plastic parts in the Clark Pump. I believe they use a borate based pickle solution.

If the system was left for 5 weeks in warm temperatures with salt water on brine side of the membranes, it is very possible that cleaning will not be able to restore them. Too much biofilm will have accumulated.

Agreed - which is why I advised him to check. The biocide of course needs to be compatible with the system, but for many sodium metabisulphite is the one supplied.

Desalination units really need to be used regularly - even recommended pickling agents are somewhat detrimental over time. We don't use ours a lot, but when at anchor for extended periods, we are glad it's there .