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How to clean a marine water strainer

This week, we bring a blog post to you from the Last Affair. Many of you that watch our Youtube Channel know that we have DreamChaser (our 51′ Formosa) as our live-aboard cruising boat. While we have been doing work on it, we also moved our 43′ Gulfstar to the slip right next to it. I use this as my office, but it is also handy to be able to stay a few days on it if needed for a big job happening on DreamChaser. It is also handy in the event we want to take off for a day sail or a weekend.
clean groco water strainerThis week I noticed that the air conditioner in the back of the boat had an error on it. I presumed it was due to low flow of water as I haven’t been cleaning the filters as often as I should on the Last Affair. I needed to clean the water strainer to improve the water flow.
We are going to be having some folks come for a visit, and I want to make sure everything is right and comfortable for them. It was time to get ahead of some of the maintenance that I may have neglected a bit.

Removing Groco Strainer for cleaningI started by closing the seacock to the air conditioner circulation pump and turned off both the pump and the air conditioner. I then climbed down in the engine room with the tools I use for this job. They are nothing fancy, it is a small quart or so throw away Rubbermaid food storage bin, a small toilet brush, and some towels. I know what you are thinking, Don’t worry, I bought the brush new for this particular use, it has never touched a toilet. That said, our toilet may be cleaner than the strainer.
I removed the lid of the Groco strainer and pulled up the filter basket and put it in my Rubbermaid container. I then put the container under the filter housing and cleaned the inside of the sight glass with the brush. I try to swirl the brush and remove it to get a bunch of the growth and stuff on the bristles. My preference is to do this rather than mix it up and let it pump through the system.

Clean Groco Strainer with toilet brushAfter doing this several times, I then scrub the inside of the glass with the brush to remove as much of the growth as possible. I put the Rubbermaid bowl under the strainer to catch water and open the seacock. My goal is to flush the gunk out and let it overflow into the container. I close the seacock and transfer this stuff to the sink to clean it.

Before I begin I put a screen strainer in the bottom of the sink because I don’t want the stuff I clean out to get stuck in my discharge lines from the sink. I get them from Amazon or the dollar store. We love these things and use them in sinks, tub, and shower. I even use one in the bottom of the fridge drain as well in the event something spills in the boat fridge or freezer it doesn’t clog the drain line.

Cleaning Groco FilterI again use the toilet brush to clean inside the strainer and on the outside running it under scalding water. I clean the top of the Groco strainer housing and remove all the crud from the drain.

The process for assembly is reversing the steps. I put the basket in the Groco strainer and turn on the seacock slightly to let water seep into it. As soon as it starts to overflow, I put the lid on finger tight. This step eliminates an air pocket forming in the line.

see good water flow and clear sight glassOnce put together, I open the seacock all the way, check for leaks, visually inspect all hose clamps. This inspection is an important step as this is all assembled below the water line and they SHOULD be double clamped.

If there are no leaks, I turn the pump back on and check the circulation. I also take this time to scrub the discharge ports as well as they do grow a few algae at that point as well. A long-handled brush from the deck does the trick.

I hope you found this information helpful if so, there is a video showing all the steps and this same process with any marine strainer. This is the same process I use for my engine strainer, generator and any of the air conditioner circulation pumps. I believe this is the same thing you would also do for a water maker input as well.


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