How do you keep your Air Cond system growth free

For you guys south of the Mason Dixon line how do you keep the AC lines clean.

I drop a 1/2 tablet of chlorine (the pool type) in the strainer every month or so and so far for the last 6 months it seems to work.*

Tim, is that the raw water strainer? *If so, I'm not sure that's such a good idea since sea water + chlorine = chlorine gas which is really, really, really corrosive. *It will react vigorously with copper forming copper chloride, which is quite brittle, and with aluminum to form aluminum chloride which is also brittle. *

Yes the raw water strainer.
Wow, you gave me a fright. What do you do?

timjet wrote:
For you guys south of the Mason Dixon line how do you keep the AC lines clean.

I drop a 1/2 tablet of chlorine (the pool type) in the strainer every month or so and so far for the last 6 months it seems to work.*

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We installed two AC units* few years ago and last fall replaced the SS stainer baskets with plastic so we could use chlorine or bromide tablets.* We're still trying to figure this out.*

I Googled "Chlorine or Bromide tablets in marine AC units".* It looks like*tablets are the method of choice in*eliminating the growth.

What's the difference from using the tablets*in an AC unit vs swimming pools?* Isn't the rate that the tablets degrade just high enough to prevent growth but low enough not cause operational issues?**

Bromine Tablets, which are about the size of a quarter and 1/2" thick are what I used when the A/C pump ran 24/7. I filled the strainer with them and replenished every time I cleaned it. In hot weather that was about every 10 days in Galveston or SW Florida. I got my tablets from Wal-Mart in the pool supply section.

Doc wrote:
Bromine Tablets, which are about the size of a quarter and 1/2" thick are what I used when the A/C pump ran 24/7. I filled the strainer with them and replenished every time I cleaned it. In hot weather that was about every 10 days in Galveston or SW Florida. I got my tablets from Wal-Mart in the pool supply section.

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*Doc, so your strainer basket has bromine in it all the time?

Why do you have to clean the strainer every 10 days. A preventive measure or is it necessary. I've checked mine when I put the chlorine tablets in it, but that's only every 6 weeks or so and I've never found anything in the strainer.*

Larry M wrote:What's the difference from using the tablets*in an AC unit vs swimming pools?* Isn't the rate that the tablets degrade just high enough to prevent growth but low enough not cause operational issues? *

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*Come to think of it most of my pool pump parts are plastic and no metal parts are in contact with water. I don't even have a SS ladder.*

Several places that I have spent the summer have had shallow thus very hot water. Clear Lake Texas is the best example. There you get more scum build up than actual barnacles. The tablets help keep the scum from clogging up the strainer. In Galveston and here in SW Florida the water, although hot, is much clearer so barnacles are more of an issue than scum. Again the tablets help.

When I said that I cleaned it every 10 days that was when we lived aboard and although the water pump cycled with the compressor it was usually on during the summer. My friends that were weekenders found that the scum and/or barnacle problem was not as bad when the water did not flow all week. Less scum because of no flow, I assume, and no barnacles because the stagnant water lost its oxygen.

If you are concerned about the Bromine on the metal strainer gasket, you can get a plastic one.

Tampa Bay and the surrounding areas like Clearwater and Palmetto have some of the worst barnacle problems that I have ever seen. When I was up there I needed a diver almost everytime I wanted to use the boat. I was told that the strong currents kept the water very oxygenated. I kept the tablets in my strainer there too.

Well, it sounds like people are using bromine tablets, which is less reactive than chlorine, but I have to say, it still makes me nervious, but since I use a keel cooler and closed loop with coolant circulating I haven't had to seriously look into it. *Sorry to give you a scare, but were I you, I would plumb in a return line back to the raw water uptake so that I could circulate seawater through the system using a small circulation pump. *You could then use a product like Barnacle Buster to safely clean out the lines, which is specifically designed to eliminate the need for using hypochloric acid directly or indirectly in cleaning out the system. *Even if using pool tablets works, most pool pumping and filtration systems are made of plastic components, and I don't think that is what you are dealing with with marine a/c units.

http://www.beardmarine.com/pdfs/Beard_Marine_Barnacle_Buster_Flyer.pdf*

Until a couple of years ago I skippered a 54 Bertram based in Barbados. The saloon a/c ran 24/7 which meant that seawater was passing through all four a/c's 24/7 as they were supplied by a common pump. I cleaned the raw-water strainer once a week, and flushed the whole system with RydLyme once a year. The yearly flush involved temporary hoses and a 5 gallon bucket to allow recirculation.

Ours is an RV rooftop system, $500-$600 new, one hour installation , (AFTER THE HATCH IS IN) .

No hoses below WL, no jellyfish cleaning at midnight and since its not "marine" its cheaper to install a new unit than call a service person.

While I have slip neighbors who put chlorine or bromine tablets in their strainers, I never have and have not had any problems. I checked the instructions for my AC unit and the manufacturer does not recommend anything.

I use Clorox toilet bowl tablets because they dissolve more slowly. Break on roughly in half and use half each time for two treatments. I also have a little strip of copper foil in every strainer basket. The copper slowly dissolves and acts like the copper in your bottom paint to keep growth down.

Keith wrote:
I use Clorox toilet bowl tablets because they dissolve more slowly. Break on roughly in half and use half each time for two treatments. I also have a little strip of copper foil in every strainer basket. The copper slowly dissolves and acts like the copper in your bottom paint to keep growth down.

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*Wow... Them there's some handy ideers :-D

Ok... so... If I have had the boat for a couple of years and never knew you needed to clean the AC circuit. I have no idea if there is any growth, but don't run my AC full-time. What should I do first? Is there a way to check it?


-- Edited by GonzoF1 on Thursday 16th of June 2011 07:00:00 AM

Keith wrote:I also have a little strip of copper foil in every strainer basket. The copper slowly dissolves and acts like the copper in your bottom paint to keep growth down.

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I'm not arguing but both you and FF have said this and I'm wondering how the copper in the strainer is any different than the cooper in the tubing in the A/C unit.* How does the strip know to give up it's cooper and the tubing*in the unit not.* Just seem redundent.

I have*no problem with the Cl or Br*in the strainer it does work.

JD wrote:*I'm wondering how the copper in the strainer is any different than the cooper in the tubing in the A/C unit.*

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*Copper strips in the strainer swirl around and bang into each other and the strainer basket. This wears the metal away and makes them shiny and gives the illusion that they are providing copper ions or some other magic antifouling property.

The truth is that copper corrodes and the products of corrosion and the sloughing off of the corrosion layer in moving water*is what provides resistance to fouling. Faster movement of water accelerates corrosion and enhances the antifouling property of copper. Copper in stagnant seawater will foul quite nicely.

Adding chlorine to the strainer will reduce fouling, it also promotes corrosion.

GonzoF1 wrote:
So what is your solution Rickster?

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*About 1 gallon of Barnacle Buster (or similar) mixed with*3 or 4*gallons of water in a 5 gallon bucket circulating for a couple of hours once or twice a year.

Hmmm... That might not be so easy for me. The raw intake is mid-ship and the output is in the stateroom aft. BUT... I guess I could rig something. ;-)

Lots*of us have been using copper strips (or tubing) for years and it does work. The copper foil I use is leftovers from the SSB installation. They are NOT shiny when I clean the strainers and I blast or brush them off to reveal the copper each time. They do dissolve over time. Last week I noticed the AC one is so thin, I'll probably replace it next change. I guess they last maybe 3 years. They don't stop the slime growth, but have never seen more than one or two barnacles.

Keith wrote:
Lots*of us have been using copper strips (or tubing) for years and it does work. The copper foil I use is leftovers from the SSB installation. They are NOT shiny when I clean the strainers and I blast or brush them off to reveal the copper each time. They do dissolve over time. Last week I noticed the AC one is so thin, I'll probably replace it next change. I guess they last maybe 3 years. They don't stop the slime growth, but have never seen more than one or two barnacles.

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*But that still doesn't explain how the strips become the sacrificial instead of the regular tubing.* Cu is Cu whether it is in strip form or in tube form.*

Oh well as long as it works.* I'm in brackish water so black*slime*is more of a problem than anything.

They're probably both doing the same thing, except the Cu foil is so thin, it's noticeable much earlier. I like the larger surface area of the foil as well.

Since the corrosion rate of copper in moving seawater is around .001 inch per year it doesn't give waterborne corrosion particles zipping through the system much chance to do anything. It's a talisman at best.

Well welcome back Rickbee. It was so nice around here while you were gone. Now we have to put up once again with you arguing about everthing you don't know about. *Don't go away mad rick, just go away.

*

And once again, it does work.

I don't see him arguing about anything... I see him stating what he thinks or understands about the subject. Let's keep it civil, please.

Hi Folks,
My forward ac condensation drains into the main bilge. The rear drains into a dedicated "bilge box" and pumps overboard. I seem to be having a black slime issue in the main bilge that creates quite a smell. I should also note that I am in brackish water most of the time. Any thoughts to address the bilge slime/smell issue? I've tried bleach but it doesn't seem to help.

Thanks,
Donny

Maybe you could connect the condensation drains to the shower drain and have the presumed grey-water pump that water overboard without having it contaminate the bilge?

timjet said:

Yes the raw water strainer.
Wow, you gave me a fright. What do you do?

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I recommend Bromide tablets.... I have three separate Mermaid units, each with its own strainer and pump.... I put a couple of tablets in each one of the strainers....and it keep growth down. I talked to Mermaid about it, and they said it was a good thing.

DonnyP said:

Hi Folks,
My forward ac condensation drains into the main bilge. The rear drains into a dedicated "bilge box" and pumps overboard. I seem to be having a black slime issue in the main bilge that creates quite a smell. I should also note that I am in brackish water most of the time. Any thoughts to address the bilge slime/smell issue? I've tried bleach but it doesn't seem to help.

Thanks,
Donny

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Donny, I would suggest that you run the forward ac condensate to a sump that has a float switch and will pump it out.

The only thing that is nastier than ac condensate in the bilge is shower water... My forward ac did the same as yours, and I never had a dry bilge. We liveaboard full time so the ac's are running much of the time, especially in summer. For the forward...I had a discharge thru-hull just above the water line...I rerouted the condensate line to it as opposed to constructing a sump and putting in a pump.

The aft two ac's drain their condensate to a sump that is float switched and pumps it overboard.... I have a dry bilge now. Smell is better also.

To get rid of the smell that lingers....try getting your bilge as dry as possible, then dump about 20 gallons of vinegar in the bilge....let it sit. You could also run the boat to swish it around or do that with a mop.... After pumping the vinegar out...and airing out the bilge...if the funky odor is still there....you may have to do a serious cleaning with TSP.

Thanks everyone. I will route the condensate drain to the shower sump. I have not detected any growth within the system so will hold off on the bromide, but keep it in mind.

DonnyP said:

Hi Folks,
My forward ac condensation drains into the main bilge. The rear drains into a dedicated "bilge box" and pumps overboard. I seem to be having a black slime issue in the main bilge that creates quite a smell. I should also note that I am in brackish water most of the time. Any thoughts to address the bilge slime/smell issue? I've tried bleach but it doesn't seem to help.

Thanks,
Donny

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The condensate has nothing to do with the salinity of the water the boat is in. The condensate is water that the system has removed from the air inside your boat.

Any manufacturer who drains AC condensate into the bilge ought to have his license to build boats revoked. It's a terrible idea.

If the AC unit is above the waterline (mine is), the best practice is to plumb it directly overboard with a hose and through hull fitting.

If not, plumb it into a shower sump (you can buy these, it's a small box with a bilge pump and float switch) and plumb the discharge overboard above the waterline.