MacGregorSailors.com

USDA reference on attached screenshot

0.5 gallon 6% bleach per 100 gallons

So I think about 1 full gallon 6% for our ballast tanks?

With about 140 gallons of water in there, that sounds reasonable.

I have kept my 26d in a marina on Lake Erie for a handful of years and have played with varying amounts of bleach in my ballast tank. I started a few years ago with using a full gallon and have reduced the amount by a cup or two each year used maybe 2 cups this past season and meant to give the tank a sniff test mid season but never did. I most definitely DID NOT add enough this year. I had my boat in from June until almost November and when I opened the valve at the haulout ramp a few weeks ago, the water was clear but the air being purged until the cabin from the ballast tank was almost gag inducing stinky. I peered into the empty tank with my cell phone camera and there weren't any zebra mussels or growth that I could see but there was definitely some algae or other bio funk living and/or dieing in there. I haven't actually measured the amount I put in each year but after reading this thread, I will probably just use a full gallon from here on out.

One note that I haven't seen mentioned elsewhere is that my daggerboard below waterline fill and drain holes do have zebra mussels hitching a ride, so that's another spot to look at for avoiding the spread of invasive species. I've never done any trailer sailing with the D but would like to start exploring different lakes and waters now that I've got a 26X also. If I decide to keep the X in the marina, I won't bleach the ballast water, as it gets emptied for motoring whenever I take it out and go fast. I'm not sure how to go about doing a 180 degree F hot water ballast tank rinse, so unless I find a place to do that, I guess I'll have to plan accordingly to make sure the X is dried out for a couple weeks before taking it to new locations.
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I just drop a couple of those chlorine pool tablets when I fill the ballast. I keep it full all season. When emptying it's clean and free of bio stuffs.

The dagger is interesting as I never thought about that as a place where mussels could grow.
Drying out for 2 weeks should kill them. Maybe spray it down with some bleach just to be certain.

As far as the ballast tank, the Mac owners manual states that if your in a marina, and do not flush the ballast regularly that you should drop in a couple of pucks of pool chlorine to keep the algae down.

I would assume that this process would also get ride of the Zebra Muscles as well, and not harm anything.


26M Manual
Page 13

"PREVENTION OF ALGAE IN THE BALLAST TANK. If you leave the ballast tank full of water for long periods, drop in a few swimming pool chlorine tablets to prevent a bad case of algae. Be cautious when handling the chlorine tablets. Follow the directions on the chlorine tablet container very carefully. Don’t put chlorine in the galley water tank"

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