Spectra Watermaker Low Output

[SV Allibeth]

I installed a Spectra Cape Horn Compact water maker this summer, tested everything, then repickled the membranes until November when we started down the east coast. We are currently in the Bahamas and have been using it every 3-4 days, however the production has fallen from 15 GPH to about 8 GPH with both feed pumps running, and basically nothing if we only run one pump.

I have replaced the filter, checked the sea strainer, checked for any blockages or kinks in any of the hoses, etc. With both pumps running, the TDS is around 280 PPM, the pressure to the 10% Clark pump is around 95 PSI, and the flow rate of the feed water is around 3 gallons per minute. So everything appears to be in spec except we are only making half the water we should be.

We did suck some air into the system while running the system underway, and I tried to bleed that out of the system by opening the pressure relief valve and letting it run for a while. The odd thing is that whenever the pressure relieve valve is opened, the water maker appears to suck air into the membranes from the 1/4" product output tube, which is then expelled once the pressure relief knob is closed again.

Has anybody had similar issues with a Spectra (or other) water maker? Any suggestions on things to try or additional troubleshooting steps? Any help would be greatly appreciated!

Ben

[tamicatana]

Clean the membrane. Do the recommended alkaline cleaning procedure

[Networker]

I have exact same water maker, replaced membrane and have exact same issue currently. I even tried all the things you did and no luck. Last thing I’m going to do is change the 20um filter, but I’ve just been learning to live with ~10gph vs 15. Keen to see if this gets solved.

[Chotu]

A really wild guess, but most other things have been eliminated.

Is it possible that the new membranes have a higher specification or something that allows less water to pass through them in a given amount of time at a certain pressure?

The new membranes might be just passing less water per hour per unit of pressure.

Could be useful to post up the exact brand and model of membranes.

I have to revive a Spectra water maker shortly so I am reading with great interest.

[SV Allibeth]

Chotu - unsure about the membrane brand as it came installed and pickled in the new watermaker. But when we first started using it it was making close to the rated 15 gallons per hour and the TDS was lower. Of course, we were also further north where the salinity was lower and the water is colder.

Networker - Have you ever seen the rated output? Do you see any output running one pump with reasonable TDS? Hearing you have a similar issue with new membranes makes me think it could be something else with the system.

tamicatana - I was hoping to save cleaning as a last resort as spectra recommends not to use cleaning as a troubleshooting step, but it is certainly possible we sucked some pollution into the membrane making water in one of the estuaries on the trip south. I also didn't think to order any of the cleaning chemicals before we left, so all I have are 4 pouches of their SC-1 pickling chemical.

[Off Trail]

I'd try a flow test with each pump to see they really providing the needed flow (measure total output by timing into a bucket), and also check the end-to-end output FW line make make sure there are no constructions there. The output tubing can be fragile.

[GRIT]

Was it a brand new watermaker when you installed it?

Have you checked your strainer, and measured the flow out the brine discharge?

When you're making water, watch the flow "ball". How far does it drop between cycles? It typically will drop only 5 or 10 psi, then pop right back up. If it drops to the bottom, that might mean a worn shuttle or internal leak.

Where in the Bahamas are you? I've had mine apart many times, and am happy to help, if you need to inspect the innards for wear.

Cheers.
Paul.

[Networker]

I replaced the membrane with a Dow Filmtec SW30-2540: Dow Filmtec SW30-2540 Seawater... https://www.amazon.com/dp/B00D43H5TO?ref=ppx_pop_mob_ap_share

My ball does drop from 10 down to the bottom, maybe something needs tightening? I still think I have air somewhere as I had the same issue, was running it while keeled over sailing and it was just gulping air.

I’m in Georgetown, Exumas for a few weeks.

[carstenb]

I'm flagging this because I want to follow - our 200T is only producing 22 liters per hour instead of 30.

I have replaced the feed pump - no joy and cleaned the entire system

[GRIT]

You're only making 10? If you're making 40 and it drops to 20 or 30, that's close to normal. If you're only making 10, there's an issue at play.

It does sound like you're taking in air somewhere.

When you release the pressure in the membrane, the product water tube will empty, that's normal.

I'll be in Georgetown just after xmas. If you're there, I can take a look if you like. We have the Cape Horn as well, and have had it apart many times, as we had wear issues with the Annular rings, and Shuttle. I'd be very curious to see if yours look like ours did.

Cheers.
Paul.

[SV Allibeth]

Flow rate of the brine discharge with both pumps running is right around 3 gallons per minute. I will run the test again with each pump individually.

Our problem definitely sounds similar to Networker - the ball drops all the way to the bottom when the clark pump cycles. We are currently in Nassau but headed to the northern Exumas tomorrow.

[Networker]

Originally Posted by GRIT

You're only making 10? If you're making 40 and it drops to 20 or 30, that's close to normal. If you're only making 10, there's an issue at play.

It does sound like you're taking in air somewhere.

When you release the pressure in the membrane, the product water tube will empty, that's normal.

I'll be in Georgetown just after xmas. If you're there, I can take a look if you like. We have the Cape Horn as well, and have had it apart many times, as we had wear issues with the Annular rings, and Shuttle. I'd be very curious to see if yours look like ours did.

Cheers.
Paul.

Sounds great, I’m doing the thorny path so I just need to see how the weather is as we plan on leaving soon after Xmas to continue on down. Let me check for air again.

[GRIT]

I have found, assuming good flow, if the product water lowers, and the ball is dropping more than usual, there's been wear or leakage within the Clark pump.

I'm happy to walk anyone through disassembly and inspection.

Cheers.
Paul.

[GRIT]

I'm leaving ft Lauderdale soon after Dec 20. If anyone needs spectra parts, I can bring them to exumas.

Tellie is in ft Lauderdale, buy from him and see if he'll drop them to me in Hollywood.

I'm happy to help.

Cheers.
Pyl.

[GRIT]

Originally Posted by Networker

I have exact same water maker, replaced membrane and have exact same issue currently. I even tried all the things you did and no luck. Last thing I’m going to do is change the 20um filter, but I’ve just been learning to live with ~10gph vs 15. Keen to see if this gets solved.

Spectra wants you to use 5 micron filters, not 20 microns. Unless you have two filters in series, then 20 first and 5 last before the clark pump.

Cheers.
Paul.