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I was talking with another Mac owner who has a slip at a marina and he mentioned he puts fresh water in his ballast tank instead of the smelly, marina polluted salt water. Just run a hose inside to the ballast. Good idea if your boat is used mostly for sailing and is in a slip.

I figure about three hours to fill at my typical hose flows of 2 gallons per minute?? Does that sound right?

Sounds ok for once a season, dont think I would want that at each setup time...

I know that when diving in salt water I need about 5 more lbs of weight then I would in fresh water to offset the incresed boyancy of the salt. So would that also mean a gallon of salt water is heavier then a gallon of fresh water? I don't think I'd sacrafice the weight to avoid a stinky tank. Especially when it's never been a problem for me before.

I thought about that idea too but all it is not worth the hassle. I use chlorine to eliminate "smelly."

How much chlorine you might ask? To quote Moe from an earlier post:

"To get a 1 part per thousand dilution, you'd need about 3 cups or 24 ounces of household bleach, for 1500 lbs of water. That's the typical 4 hour contact time sanitizing dilution for freshwater plumbing systems. You'd only need about 3/4 of that with the more concentrated "Ultra" bleach. A pint (2 cups) of that should be close enough."

I just go to Walmart and buy the small Chlorox bottle, add it to the tank and filler up. Works for me. I have several bottles in the storage area.

Here is where the idea of filling the tank with fresh water breaks down.
You are on the lake and want to go fast under motor power and so you empty your ballast. Ski, tube, whatever, having fun, then you have to go back to the marina. Personally, I like to have all boards down and the ballast full if I go back to the marina in lots of wind. So I would rather pour some chlorox in the tank, re-fill it and motor back to the marina.

Plus I would rather spend my time sailing and not filling a tank with a water hose with low pressure.

Randy, aren't you on "fresh water"?

Do you really want to dump a bottle of chlorox into your lake every time you dump your ballast?

The water I sail on is BROWN.

Algae, zebra mussels, plankton, sea gull poop, catfish poop, you get the idea.

This is my first season out so I cannot expound like a sailing expert.

HOWEVER, I have some buddies who have ballast boats who say that even in the pristine sacred waters of windy Kansas, no chlorine means the smell of sewage.

I was using a 1/4 chlorine tablet every few weeks.It damaged my air plug and gave off a huge amount of gas that when I opened the ballast valve on the stern, a blast of chlorinated fumes shot out. TOO MUCH chlorine maybe???

Kept my tank clean though.

Moonie - my guess is the gas isnt from the tablets, its just a result of expansion from the ballast slowly warming up during the season,

I noticed the same thing on Catigale when I put a cup or two of bleach in the tank,and its correlated with temperature changes, not when I put the bleach in. I only do this a couple times during the season

Do try and avoid getting bleach near your rubber plug - it eats 'em up rally nice.

Catigale wrote:Moonie - my guess is the gas isnt from the tablets, its just a result of expansion from the ballast slowly warming up during the season,

I noticed the same thing on Catigale when I put a cup or two of bleach in the tank,and its correlated with temperature changes, not when I put the bleach in. I only do this a couple times during the season

Do try and avoid getting bleach near your rubber plug - it eats 'em up rally nice.

Doesn't the ballast expansion stress the ballast tank to a point of it causing damage? I'm sure the f/glass can only take so much stress and if the chlorine contributes to the expansion, the gas needs to go somewhere. A bit like eating Baked Beans.

Now I'm wondering how well that rubber plug can seal? But I'd bet the fiberglass has a lot of flexibility, and that the vent or intake valve would seep before damage to the hull. Finally ... there's yet another benefit to running a passive vent hose to some thru-hull!

Mine is a simple hose under the v-berth and up to the bow thru-hull. You can see three different approaches in Mods/Misc, but I liked Tahoe Jack's best ... his includes a battery-operated "full" buzzer.