Steadily increasing salinity in Spectra Catalina 300

[LifesBetterWhenYoureBeating]

I've recently purchased a boat with a Catalina 300 (MPC 5000). It is operating without any leaks (after replacing both end caps on the Clark pump), and in the beginning the display reports a product flow of 8.9GPH and salinity of 160, but then the salinity steadily increases while the product flow declines. These are the numbers I saw on the last run, taken every 5 minutes:

GPH Salinity
6.5 224
4.9 288
4.4 320
3.8 368
3.2 448
2.4 528
Stopped manually

If I manually stop and start again, the salinity starts almost as high as it was when stopped, and the product flow as low as when stopped. Only after a fresh water flush the salinity and product flow go back to the initial numbers.

I'd appreciate any suggestions on how to troubleshoot this further as this makes my Watermaker useless since the amount of water it makes is barely enough to offset what it uses during the fresh water flush

[GreenWave]

How old is the membrane? Have you replaced the pre-filters recently?

[LifesBetterWhenYoureBeating]

Originally Posted by GreenWave

How old is the membrane? Have you replaced the pre-filters recently?

The membrane is from 2017 and according to the mpc5000 this system has only 88h of run time, and in pretty sure that's true. The prefilters are brand new

[djs]

I’ll be following this hoping that cruisers with more experience than I chip in. We’ve run a watermaker for three years now and my guess / bet would be that the membrane needs replacing. If it’s been out of use for so long, and just 88 hours use in 5 years means there’s been long periods of non use, chances are the membrane’s dried out.

But I’ll following to see what other more knowledgable heads say.

[GreenWave]

Originally Posted by djs

I’ll be following this hoping that cruisers with more experience than I chip in. We’ve run a watermaker for three years now and my guess / bet would be that the membrane needs replacing. If it’s been out of use for so long, and just 88 hours use in 5 years means there’s been long periods of non use, chances are the membrane’s dried out.

But I’ll following to see what other more knowledgable heads say.

Good point - wonder if OP had the membrane pickled prior to using it?

[LifesBetterWhenYoureBeating]

Yes, the membrane was pickled

[Pitchondesign]

All watermakers have o rings in the pressure vessel to keep the brine water separated from the product water. Even a slight leak in those o rings will allow brine water to mix with product water, causing exactly the symptoms you are seeing. If you replace those o rings, use silicon grease only. Regular grease will degrade the o rings.

[Tellie]

First, your numbers are all wrong. There is no way a Catalina300 will make those PPM readings at such low production. I'm assuming you are reading these figures from your control panel. These numbers can easily be fudged if you know how to get into the program and change them. If those numbers are even close to reality (very questionable) you have a pressure and flow issue from the feed pump, Clark pump, or both. The fact that you get better readings on startup is because of the freshwater flush. You are just reading the PPMs of the fresh water until the saltwater starts to enter the system. It may be time to have a Spectra tech with proper gauges to take a look and re-set the controls back to factory specs to start.
Does your system have an analog pressure gauge on it? If not, I would highly recommend that you install one. This will tell you real numbers on the feed input pressures and the symmetry of the Clark pump. Without these numbers changing a membrane is just guessing and I'm willing to bet you have other issues.


GPH Salinity
6.5 224
4.9 288
4.4 320
3.8 368
3.2 448
2.4 528

[rphdiego]

The pickeling solution is only effective for up to 6 months.

[LifesBetterWhenYoureBeating]

Originally Posted by Tellie

First, your numbers are all wrong. There is no way a Catalina300 will make those PPM readings at such low production. I'm assuming you are reading these figures from your control panel. These numbers can easily be fudged if you know how to get into the program and change them. If those numbers are even close to reality (very questionable) you have a pressure and flow issue from the feed pump, Clark pump, or both. The fact that you get better readings on startup is because of the freshwater flush. You are just reading the PPMs of the fresh water until the saltwater starts to enter the system. It may be time to have a Spectra tech with proper gauges to take a look and re-set the controls back to factory specs to start.

I waited a few minutes until the control panel's reject light was off and the good light was on before I started taking those readings.



I'm not going to be near a spectra tech any time soon. Is there any way I could reset the controls myself? I've used the programming interface of the control panel before...

Does your system have an analog pressure gauge on it? If not, I would highly recommend that you install one. This will tell you real numbers on the feed input pressures and the symmetry of the Clark pump. Without these numbers changing a membrane is just guessing and I'm willing to bet you have other issues.

I do have an analog gauge. Here's a video I made at the time: https://photos.app.goo.gl/cQx36fgdojB63eBe7



Is it true that the pickling solution is only good for 6 months? I'm pretty sure this system was pickled for longer than that

[rphdiego]

I install and service water makers on boats. The highest concentration of SMBS (Sodium Metabisulphite) that is recommended for pickling is only effective for 6 months. After that the worse thing for the membrane is it drying out. You can try cleaning the membrane but at this point it sounds like its time for a replacement.

[smallchange]

I’ve had a spectra Watermaker with The MPC 500 controller for 5 years and learned the best problem solving starts with a call to the spectra tech. They are great and patient and walk me thru troubleshooting over the phone. Their phone is (415) 526-2780. I’m no expert just learning on the job,
that being said there are several conditions and components to verify.

1. Check to be sure the pre filters are clean. If your making water in a muddy bay like the Chesapeake they will clog up in as little as a half hour of making water. Sometimes I would replace the filter and it would clog up with fine sediment almost instantly if I wasn’t in clear water.

2. Verify the raw water intake is allowing water in. Close the valve. Remove the hose to the thru hull and slowly open the valve. If water gushes in your good.

3. Verify the booster pump is working (usually located by the seawater intake. Mine went out and reduced flow to the Watermaker and the Watermaker would shut down after only a few minutes. A new one was fairly inexpensive and easy to put in.

4. Verify the brine discharge valve is open. Visually see the water is freely discharging overboard while running the Watermaker. The line could be partially linked or clogged.

5. The diversion valve, located on the end of the Clark pump tubes, sometimes sticks and diverts all water overboard. This doesn’t sound like your problem but I’ve heard it’s a common occurrence and happened to me. Initially a light tapping on the diversion valve with a mallet while running got it unstuck but after a few times I got a new one. Pretty easy replacement.

5. Those are some of the easy checks. Then to verify if the Clark pump O rings are the problem have the Spectra Tech walk you thru that check. A new Clark pump at least for my Catalina 340z system runs around $3000 but you can get a rebuilt one for about $1000 if you turn in your old Clark pump. I did that and it made my whole system run really well after struggling to troubleshoot for a month.

6. I’ve never had to replace the membrane. So can’t help you there. Good luck but let us know what happens.

[Tellie]

Originally Posted by gsalgado

I waited a few minutes until the control panel's reject light was off and the good light was on before I started taking those readings.

Looking at your last reading on the numbers you posted. The last was 2.4gph at 528 PPMs. Your membrane is fine. Once your production is restored the gph will go up to around 12gph and your PPM readings will drop and fall in line with approved specs. I want to re-word what I said previously about the numbers being all wrong. The reason the numbers are way off is not the membrane but your pressures and flows are not up to spec. That is why the numbers are all wrong on the membranes output. You will need to perform a flow test on the brine discharge. Mark a five gallon bucket in accurate one gallon increments. Using your brine discharge pickling hose, direct the other end into the bucket. Start your system manually. Disregard the first gallon, then time the next few gallons to see how long it takes to produce one gallon. Do this a few times to get a good average. The feed pump should be producing 2.3 gallons per minute. Anything lower than 2gpm and there's a feed water pump issue. This test is needed but I doubt this is going to be an issue though. Once we eliminate the feed pump we can start to look at the Clark pump as the most likely culprit here.



I'm not going to be near a spectra tech any time soon. Is there any way I could reset the controls myself? I've used the programming interface of the control panel before...

Sure, it's a Spectra, These are the easiest systems to work on in the field, it's the way they were originally intended. But we are getting a bit ahead of ourselves. First we have to figure out what's mechanically wrong with your system and resolve it. Once that's done we can easily re-set the electronics to read and match actual production accurately.








I do have an analog gauge. Here's a video I made at the time: https://photos.app.goo.gl/cQx36fgdojB63eBe7

The video of the gauge is great, it helps a lot. The gauge is showing asymmetry in the Clark pump, especially on one stroke. If you look carefully you will see one stroke is 80-90psi. That is the good side that is carrying all the production rate. The 75-85 psi stroke is the problem side. You'll notice that the needle sits at the 75psi for too long then quickly jumps to the 85psi then right back down to the 75psi again. This cylinder is having a hard time producing enough pressures thus the very low production showing on the control panel.


Is it true that the pickling solution is only good for 6 months? I'm pretty sure this system was pickled for longer than that

It all depends on what pickling solution was used. If it was pickled with Spectras SC-1 then it ios good for six months. If it was pickled with Propelyne Glycol (-50 Pink) then it can sit for a few years. I always recommend PG-50. Not for it's pickling longevity but rather for the great protection it affords the internal parts of your watermaker. PG-50 just protects everything so much better.


Let me know what the flow test shows and if you want we can move on from there.

[LifesBetterWhenYoureBeating]

I was able to do a flow test today. Since my batteries were not fully charged I decided to run the engine at the same time. That caused a significant increase in the initial production compared to what I saw in previous runs.


Initially the control panel was reporting around 11GPH and I measured 20l of discharged brine in 157 seconds (not very accurate as I don't have a big enough bucket and a significant amount was spilled while replacing bottles). Unfortunately part of the product water was spilled, so I don't have numbers for it. However, the product water from those minutes had a strong smell/taste of sulfur, something I hadn't seen in any of my previous runs. The following video shows the pressure gauge at that time: https://photos.app.goo.gl/DdtjGXoi6qaBLgFw5


The product flow reported by the control panel kept decreasing and when I turned off the engine it went down to around 5GPH. At that time I measured the discharge again and got 8.6L in 72s (again not accurate, probably significantly more than 8.6L). The product water now had no smell/taste, and this video shows the pressure gauge at the time: https://photos.app.goo.gl/ecwqfbNS5upNHzUT8


I hope this helps identifying where the issue may be. Please let me know what tests I should perform next.

[Tellie]

The pressure gauge shows us that you Clark pump is asymmetrical and losing a good bit of pressures on one cylinder. this is what is causing your numbers to be way off. Look closely at the pressure gauge and you will see one stroke the needle climbs slow but steady, the next stroke the needle stays at it's low spot until the last second. This is the bad cylinder. It's time to have the Clark pump serviced.