Plugging prefilters

[Bigsalmonfish]

Does anyone have advice on how to extend the life of your watermaker prefilters in plankton/algae rich water? My 20 micron plugs after several hours of running.

 

[O C Diver]

Have you considered switching to a larger filter housing? Maybe post a picture of your current filter and housing.

Ted

 

[Stabi]

TwistedTree should chime in shortly with his media filter solution. It works, down side is that it takes up quite a bit of real estate.

 

[Pete Meisinger]

I had the same problem. I got rid of the filter. I never drink the water from my tanks, just use it for washing and sometimes boiling corn.

Coffee, drinking, iced tea, tooth brushing and pill swallowing uses bottled water.

pete

 

[Bigsalmonfish]

I've heard about the use of a sand filter. Would like to find a diagram and one small enough.

 

[C lectric]

Many filter mfgrs. make several different sizes of filter housings that can take some LARGE elements. Maybe also twinning those housings would do the trick.
Just choose a suitable element for the housing that will remove the offenders. You likely won't find them on sites like Amazon although I won't say can't.

Considered an industrial type filter? Some can be backwashed although that may be more than you want/need and they will be larger, maybe too large.

 

[Larry M]

What size and type filter does the manufacturer recommend? We use a pleated vs a wound prefilter. The pleated filters have more surface area than a wound filter and are easier to clean.

 

[Stabi]

I sourced a 7x35 tank and a manual valve from here.
https://aquatroltech.com/
Using Twisted's suggestion, instead of sand I used Micro Z.
Last summer was my first year and it worked great.

 

[Chrisjs]

We made great water offshore and in the Bahamas - no problem. When we got back to the ICW it was all over. There was so much crap in the water that it simply was not worth the effort. Plus apart from the algae etc, there is coliform contamination, oil, etc. Your RO membranes are not capable of efficiently removing coliforms or other bacteria. We did find we could rinse (back flush) prefilters a few times using a hose on the swim platform. Do not honestly think you will achieve much by having sequential prefilters with tiered porosity.

 

[WayneDana2]

I made all my own water for years and developed a system.

1) use 30 micron filters. Buy them from Home Depot or similar, instead of from a water maker manufacture or marine store. Much cheaper and well suited to purpose.

2) Change them all the time. More often than you need to. But don't throw them out, just tie a rope to them and trail them overboard over night at anchorage, they will rinse themselves.


3) Do NOT make water in anything other than clear ocean water. If it has algae in it your membrane will not last long even if the filters are clean. Buy water or go out to the open ocean to make water if need be. Filtering is NOT the answer to unclean water.


4) Do not make water in a marina. yuck.

 

[Bigsalmonfish]

I sourced a 7x35 tank and a manual valve from here.

https://aquatroltech.com/

Using Twisted's suggestion, instead of sand I used Micro Z.

Last summer was my first year and it worked great.

Did you put this in lieu of the 20 and 5 mic filters or did you put forward of them?

 

[Lepke]

I use washable 20 & 5 micron prefilters and a 1 micron disposable before the HP pump. My housings are 4.5x20 and the filters go a long time between cleanings. The 1 micron last about a year and I make all my water, liveaboard, have laundry, dishwasher, etc.
I winter on the Columbia River and make water there, too. That's why I have the washable filters. No issue with silt or algae.

 

[Stabi]

Did you put this in lieu of the 20 and 5 mic filters or did you put forward of them?

The media filter is plumbed ahead of the 20 & 5. We were on the boat for 5 months last year and only had to rinse the 20 mic twice, never did rinse the 5. I would backwash the media filter for 15 minutes about every 10 hrs of run time

 

[C lectric]

Better advice than mine.

 

[Ken E.]

Big, I'm in about the same locale as you and have no problems with 5 mc filters, which I change annually. The best advise was mentioned above: only make water in open water, away from anchorages and marinas. That procedure has worked for me for many years.

 

[twistedtree]

I struggled with this for years, and was forming the opinion that a water maker was more trouble than it's worth. Then I installed a media filter, and made nearly all my water for the next couple of years. To me, there is no substitute if you are in biologically rich waters.


Let me also venture a guess that you have a Spectra watermaker? By all indications, they plug up much faster and easier than other water makers.

 

[Bigsalmonfish]

I struggled with this for years, and was forming the opinion that a water maker was more trouble than it's worth. Then I installed a media filter, and made nearly all my water for the next couple of years. To me, there is no substitute if you are in biologically rich waters.


Let me also venture a guess that you have a Spectra watermaker? By all indications, they plug up much faster and easier than other water makers.

I have a Aquamarine About 40gph so I am pumping lots of water through the filters. A media filter seems like the solution to this. Just trying to find one that makes sense

 

[mvweebles]

Knowing that TT has a fantastic blog, I found his post on media filtration. Thought I'd share - many thanks as always to a super-helpful fellow forum member!

Adventures of Tanglewood: Water Maker Media Filter

 

[bayview]

IMO water makers are not for use in anything but clear water. I think they are primarily desalinators that must prefilter other stuff to get to the water they properly work on.

 

[twistedtree]

I have a Aquamarine About 40gph so I am pumping lots of water through the filters. A media filter seems like the solution to this. Just trying to find one that makes sense

Well, that somewhat blows my theory that Spectra water makers are more susceptible to this. They generally have much lower pressure boost pumps (~5-10psi) vs typical AC powered water makers with closer to 30 psi.


Regardless, in my experience a media filter is the ticket, at least for the PNW and the NE US. And it's not because of running in dirty water because I only make water out in open seas. It's all about the microbial life in the water. Basically little sea beasties.

 

[Bigsalmonfish]

Well, that somewhat blows my theory that Spectra water makers are more susceptible to this. They generally have much lower pressure boost pumps (~5-10psi) vs typical AC powered water makers with closer to 30 psi.


Regardless, in my experience a media filter is the ticket, at least for the PNW and the NE US. And it's not because of running in dirty water because I only make water out in open seas. It's all about the microbial life in the water. Basically little sea beasties.

Certain areas just have more beasties...going to research the addition of a media filter and that is on the list after the Covid cruise. I appreciate all the input

 

[foreverunderway]

Your RO membranes are not capable of efficiently removing coliforms or other bacteria. .

This is patently untrue.

However, fuel oil will damage the membrane so we do not operate our watermaker in oily water such as one would find in a busy commercial harbor.
If it is impossible for you to move to another place to operate your watermaker, then you could add a prefilter to what you have, say a 30. That would help.

 

[foreverunderway]

I had the same problem. I got rid of the filter. I never drink the water from my tanks, just use it for washing and sometimes boiling corn.

Coffee, drinking, iced tea, tooth brushing and pill swallowing uses bottled water.

pete

The filters are just to protect the high pressure pump and the membrane and have nothing to do with water quality.
I don't understand folks who pay thousands of dollars for a watermaker and then don't drink the water. What comes out of the watermaker, if your numbers are acceptable, is as good as, or in many cases, better than bottled water. If you don't like the taste, even though the water is safe, just add another spigot in the galley and feed it through a carbon block filter.
I don't believe there is a legal water quality standard for bottled water in the US, so in some cases it might not be much better than tap water.

 

[Chrisjs]

"patently untrue"
If you read my post it says:
"Your RO membranes are not capable of efficiently removing coliforms or other bacteria."
While a totally integral RO membrane will remove much in the way of bacterial contamination, cysts, etc and can reduce viral load it can not be trusted to remove 100% of bacteria (coliforms) and is not very efficient with viruses. Pore size specifications for RO membranes look extremely small so it may appear that it should do the job. The reality is that RO membranes are not intended for this function, and are not integral to the extent that they can assured of performing this function. And further, stresses on the membrane during its useful life span increase the likelihood of small particles passing through, as is demonstrated by water TDS increasing over time. In any industrial seawater desal plant, water would be sterilized after RO. Can you get away with it? Probably, depending on the source of the water you are putting through the RO. Hence back to not trying to make drinking water from dirty water - where this discussion bega, I believe. Check out the reference below:

https://www.freshwatersystems.com/blogs/blog/how-to-remove-bacteria-from-drinking-water.

p.s. I did once run a large water purification company

 

[foreverunderway]

"patently untrue"
If you read my post it says:
"Your RO membranes are not capable of efficiently removing coliforms or other bacteria."
While a totally integral RO membrane will remove much in the way of bacterial contamination, cysts, etc and can reduce viral load it can not be trusted to remove 100% of bacteria (coliforms) and is not very efficient with viruses. Pore size specifications for RO membranes look extremely small so it may appear that it should do the job. The reality is that RO membranes are not intended for this function, and are not integral to the extent that they can assured of performing this function. And further, stresses on the membrane during its useful life span increase the likelihood of small particles passing through, as is demonstrated by water TDS increasing over time. In any industrial seawater desal plant, water would be sterilized after RO. Can you get away with it? Probably, depending on the source of the water you are putting through the RO. Hence back to not trying to make drinking water from dirty water - where this discussion bega, I believe. Check out the reference below:

https://www.freshwatersystems.com/blogs/blog/how-to-remove-bacteria-from-drinking-water.

p.s. I did once run a large water purification company

Every watermaker professional I know, disagrees with your statement if the membrane is fully intact. Most say an UV filter is a waste
of money because the membrane will not pass anything as big as a bacteria.

ps. I'm a licensed chief engineer, steam or diesel, unlimited horsepower and I built my unit from pieces.

"bacteria will be removed via reverse osmosis due to size exclusion (i.e. the bacteria are larger than the pores in the reverse osmosis membrane so they can't pass through)."
See, one can find anything one wishes on the internet. lol

 

[Chrisjs]

Have you ever built an industrial seawater desal plant??

 

[captmikem]

Sand filter is the best, but you can clean your pre filters and get several more uses from them by soaking them in tidy bowl cleaner. I have used this a lot and as long as you do not damage the filter physically, it cleans them and they work like new.

M

 

[RoseLoper48]

Plankton Filter

I have a Plankton Filter on the intake for my watermaker. It is a stainess steel mesh that is very effective in filtering out plankton. In over 10 years my pre-filters normally last 2-3 times as long as others in the same waters. I have a Spectra Water Maker and they sell the Plankton Filter.