Keeping Saltwater Ballast in tank for 6 months

[yukonbob]

On top of the chlorine I try and change the water regularly.

[bartmac]

Not so much regarding water in the ballast tank but the hull itself.....spent 11 days in tidal river water with lots of agriculture up stream over Xmas....and wow the amount of growth on the Mac was amazing.The locals put it down the amount of nitrogen available from run off ie sugarcane etc???not sure whether the creatures which adhere are using N

[seahouse]

Yeah – it would take a ton of salt to reach the concentration (saturated) needed to kill stuff in the ballast, especially so in sea water, and less so in fresh water.

Fresh water is toxic to salt water organisms, and salt water is toxic to fresh water organisms. With some exceptions. Salmon come to mind.

In salt pools chlorine is still the sanitizer, the only difference is that the chlorine is generated by electrolysis of the salt ( sodium, chloride) at electrodes, instead of being added directly. And salt pools are a fraction of the salinity of sea water too, so you won't be swimming any faster in them than fresh.

In fresh water I found that if I changed the ballast water often enough (say, every week) odour was not a problem. When I hadn't changed it and noticed it was getting rank, I used a cup of liquid chlorine (pool shock, which is 2X more concentrated than bleach) to sanitize (it hadn't been changed for several weeks). A few days later when I checked it was good, and still at the end of the season (a month and a half) it smelled clean when I finally dumped it out at the ramp.

Both strategies worked equally well for me, but in the future near the end of the season I will be adding a cup to the ballast to sanitize for a while before haul-out for the winter storage.

A chlorine tab is a very strong oxidizing agent – it literally “burns” whatever it comes into contact with, even (especially) under water. To be sure, I would want to know that there was some ongoing wave movement when adding a tab so that it's doesn't stay in contact with one point of the fibreglass hull for any length of time.

-Brian.

[FinallySailing]

The most environmentally safe biocide for your tank is salt at high concentrations (>5% by weight), but thats A LOT of salt in your tank. Consider that you're talking about 100lb. bag of salt poured into your tank to get above the salinity required to definitely kill everything in seawater

I've got 1200 lbs of water ballast in my "S". That's 544 kgs. 5% of this is just around 27kgs or just under 60lbs. Just over one 25kg bag that you can get over here for around £6. That is assuming you are in fresh water. In the sea, the salinity of salt water is already 3.5 % at average. To lift the concentration above 5% you'd be using quite a bit less. I think this is quite a viable option. The reason why I initially brought this up was because the "antifreeze" effect of dissolved salt in water. It will cause a depression of the freeze point of water, and as such the temperature your ballast water will start freezing. Let's say you are in a colder climate, you have your Mac permanently moored with your water ballast full and you suddenly have a temperature drop. Frozen water expands ...

[dlandersson]

1200 lbs. of good ol' white lighten' would make a nice li'l party. And good ol' white lighten' is antiseptic and non-freezing also.

The most environmentally safe biocide for your tank is salt at high concentrations (>5% by weight), but thats A LOT of salt in your tank. Consider that you're talking about 100lb. bag of salt poured into your tank to get above the salinity required to definitely kill everything in seawater

I've got 1200 lbs of water ballast in my "S". That's 544 kgs. 5% of this is just around 27kgs or just under 60lbs. Just over one 25kg bag that you can get over here for around £6. That is assuming you are in fresh water. In the sea, the salinity of salt water is already 3.5 % at average. To lift the concentration above 5% you'd be using quite a bit less. I think this is quite a viable option. The reason why I initially brought this up was because the "antifreeze" effect of dissolved salt in water. It will cause a depression of the freeze point of water, and as such the temperature your ballast water will start freezing. Let's say you are in a colder climate, you have your Mac permanently moored with your water ballast full and you suddenly have a temperature drop. Frozen water expands ...

[Crikey]

And when you're finished with the moonshine, you could just pee into it. Probably about as effective!

[Seapup]

After a season, my ballast smells just like a swimming pool. Before using the chlorine, it would knock you out with the rotten egg smell.

Stick to what works.

For the fun of it I grabbed some 99% dichlor from my tub while home yesterday. I tossed in 5 tsb which should be enough to get the tank to about 100ppm free chlorine/superchlorination. Maintenance/sanitation is 3-5ppm. I will test it again in a few days, and I am guessing it will be back to 0 ppm.

[seahouse]

Seapup –

Dichlor is around 60% chlorine as a granule. You are showing a liquid there, did you mean to say sodium hypochlorite liquid, which is closer to 10%? I ask because that would change your concentration estimates.

But yeah – 100ppm is 10X what it needs to be for a normal pool “shock”, but if it's really dirty inside, and you are starting out with 0 ppm, pH-unbalanced water (unlike you would be in a pool or spa), even that won't get you an effective “kill”, and chlorine will continue to be consumed after that. (That's also way outside the range of most chlorine test kits, too).

Otherwise, if the ballast is sealed and effectively sanitized, the chlorine residual should maintain itself for more than a couple of days, especially in the dark.

-Brian.

Note: If the ballast has been "let go" for too long, no practical amount of chlorine can truly sanitize the ballast. Only mechanical removal will work, and that's not practical inside a ballast tank, either.

[Seapup]

Dichlor is around 60% chlorine as a granule. You are showing a liquid there, did you mean to say sodium hypochlorite liquid, which is closer to 10%? I ask because that would change your concentration estimates.

Thats my ballast water, its been in there about 3 weeks and seemed clean. I used 99% dichlor granules which is about half chlorine and half CYA. Standard pool trichlor tabs are higher chlorine, but I figured for a boat most people would pick up the $1 shock bag of dichlor which is generally 49% dichlor vs 99%, so I mentioned the concentration I used.

[seahouse]

Yeah- the ballast water looks pretty clear I see, it was the vial I was wondering about- what's in that - is that part of the test kit?

-B.

ps- I like the redo you did of the ballast opening- for a more positive seal than the factory setup.

[Kittiwake]

..... Keep the valve closed and you will be fine. Its dark, sealed and nothing will live in there. Our X stays in a saltwater 9 months a year. No need for chlorine. ......
I know adding chlorine is mentioned in the manual as an option, ....[but].... The free chlorine would be used up rapidly and then you just have a tank of plain ol water. You could certainly put it in, but it would have zero disinfectant value after a very short amount of time (unless you want to keep adding more every few days.)

Certainly the chlorine will break down quite rapidly; but when it has done so it will have produced a sterile sealed compartment of water (ie. the water in the ballast tank will contain no live organisms to cause trouble). Of course next time you empty and refill the ballast tank you will acquire a whole new population of organisms. And I have always found it interesting that people working with marine toilets have discovered that bacteria which grow in relative darkness and in the absence of oxygen ("anaerobes") can be particularly smelly.
Kittiwake

[seahouse]

The problem with using chlorine compounds as contact sanitizers is that they need to be used on already "clean" surfaces to be effective. So if the boat is new, and the ballast walls are smooth, then you'll be more likely to be successful at getting a good "kill". But if there is a buildup of "crud" on the ballast walls then the chlorine compounds will be unable to penetrate that barrier and reach the organisms underneath. Some organisms produce their own protective barrier (such as "slime") to "hide out" behind, and that effectively shelters them from the chlorine compounds. That's why I mentioned that mechanical removal (brushing, scrubbing) inside the tank might be necessary, but that's a difficult task, so an effective "kill" is not practically attainable, and a chlorine residual will have to be maintained.

As a matter of reference, on shutdown I annually shock (to ~10ppm) my pool in October, air for a few hours, then cover it with an opaque cover until April, when the filter and solar heaters are activated, but not the chlorinator. It then runs for another 3 or so weeks, and at that time is opened with a left over residual of 3-5ppm. This is not what you would likely find with the water in your ballast tank because the water has not been chemically optimized, stabilized (cyanuric acid) and balanced, but it does give an idea of what is easily, and repeatedly, attainable after ~6 months when you start out with "clean" surfaces.

The temperature starts out in the 60's, drops to freezing, and back up again during this period. While the colder temperatures will have some inhibiting effect on growth, witness the algal blooms from nutrient loading that happen in the Great Lakes all throughout the winter months, and even under the ice cover. (When we get one)!

Yeah Kittiwake- it's no surprise that toilet systems stubbornly support anaerobiosis. Digestion in our guts requires anaerobes, more volume of them are produced than are needed, and we constantly inoculate the toilet with them. Eouooo!

- Brian.

[Dreamcatcher]

I keep a few bottles of chlorox (the smallest generic brand you can buy at Wal-Mart. I pour one bottle into the ballast tank (use a funnel) at the beginning of the season. The first year, it stayed there all summer. No rotten vegetation smell. Since, I have been emptying the ballast tank sometimes when running on the motor, and sometimes I forget to replenish the chlorox. Still no rotting veggie smells.

[seahouse]

Yeah - a funnel makes it much neater, I use the cut-off top of a 2l pop bottle. The bottle neck fits down in the hole perfectly, and I can lift it out and leave it right inside the catch basin around the hole, so no bleach drips anywhere.

In Canada, Chlorox is also known as "Javex".

Dreamcatcher - fresh or salt water?

-B.

[Seapup]

it was the vial I was wondering about- what's in that - is that part of the test kit?

Yeah, its part of my my reef test kit. I periodically test for chlorine after the ro/di to make sure the carbon is working. Our incoming water is around 3ppm.


When I tested the water in my ballast over the weekend it showed its back to no detectable chlorine.

This is not what you would likely find with the water in your ballast tank because the water has not been chemically optimized, stabilized (cyanuric acid) and balanced, but it does give an idea of what is easily, and repeatedly, attainable after ~6 months when you start out with "clean" surfaces.

That is all I was getting at originally. Chlorine itself will react and be down to zero in short order. It will kill whatever is in there, but don't expect there to be sanitizer left after a few days. Even when the CYA is built up my spa chlorine level will be back down to nil when covered and unused for about a week.

The scientific magregor manual "drop in a few pool tablets to prevent a bad case of algae" sounded to me like it was tested right after they measured 24mph with a 50hp.

One 3" tablet treats 10,000 gallons. So a few may be a bit overkill