Testing / Touching up Fiberglass Fresh Water Tank?

[antoha]

Hello folks;

I just winterized my (100 gal?) freshwater tank, and thought I'd take a photos through the inspection port. The tank is in the deep keel (tank is 4 ft deep? 5? I didn't measure), and looks to be in decent shape from what i can tell - except there's some mold, and i can't quite figure out what kind of cracks on the bottom (or maybe that's dirt, but looks like crack lines). I believe it's just cloth, no gelcoat there.

So the questions I'm trying to answer now are: (1) is this a problem? (2) how to fix? (3) how to wash? (it's deep and the inspection port is probably a 5" hole.) (4) where's the black stuff coming from? (I wonder if that's the deep bilge leaking in there, the black spot is in the right location; we don't drink tank water but that would still be unpleasant.)

Thank you in advance, and happy holidays!
Anton

[antoha]

That's about a gallon of the pink stuff at the bottom of the tank. The 100 gal estimate is from how long it takes the freshwater system pump to empty it (I have an old 3 gpm diaphragm PAR model 36950-1000 pump).

[zboss]

You may be at the point that it would be easier and cheaper simply to put a water bladder in place after a basic cleaning.

[thinwater]

Originally Posted by antoha

Hello folks;

I just winterized my (100 gal?) freshwater tank, and thought I'd take a photos through the inspection port. The tank is in the deep keel (tank is 4 ft deep? 5? I didn't measure), and looks to be in decent shape from what i can tell - except there's some mold, and i can't quite figure out what kind of cracks on the bottom (or maybe that's dirt, but looks like crack lines). I believe it's just cloth, no gelcoat there.

So the questions I'm trying to answer now are: (1) is this a problem? (2) how to fix? (3) how to wash? (it's deep and the inspection port is probably a 5" hole.) (4) where's the black stuff coming from? (I wonder if that's the deep bilge leaking in there, the black spot is in the right location; we don't drink tank water but that would still be unpleasant.)

Thank you in advance, and happy holidays!
Anton

I really don't think you have anything to worry about. The cracking is the result of resin puddling. It has probably been like that since a few years after the boat was built. The dirt is simply growth from what ever you loaded in there over the years; sure, tap water is chlorinated, but only for a few days.

You can probably clean it well with a long-handled toilet brush (extend the handle with a pipe over it) and a strong alkaline cleaner like 1/4 cup/gallon TPS with a few 1/4 cup per gallon bleach (more does not actually help). You don't need to use much just dip the brush and scrub. Rinse, and then fill the tank with 100 gallons of water and 2 cups of bleach (ANSI standard) for 4 hours. Rinse, and you're done.

A carbon block filter (NSF 53 rated) will have it tasting like bottled water.

Tap Water that’s Better than Bottled - Practical Sailor Print Edition Article

If you thought the bilge was leaking in there, why didn't you leave the tank MT and let some water into the bilge? Don't wonder.

And there is really no good reason to put pink stuff into an MT tank. That will take fore ever to flush through and is not needed. Additionally, mold and bacteria will grow in the pink stuff, making it funky by spring--this is probably the most common winterizing goof. It is MUCH better practice to leave the tank bone dry over the winter. Only pu the plumbing.

[Privilege]

Give it a quick power wash, fill it up with water, dump a couple of cups of bleach in there. When you empty it out you'll have a much better idea of what you are facing.

[Cheechako]

I'm surprised a water tank isn't gelled in there...?

[Sailorman Ed]

We use vodka or gin, whatever is cheaper, smells better and is no problem in the spring.

[antoha]

Thank you all! Will do the washing as suggested.

I'm still hoping I won't need to do anything drastic (and using a bladder would require major work - cutting it open, etc).

What's MT, btw?

[chris95040]

Originally Posted by antoha

Thank you all! Will do the washing as suggested.

I'm still hoping I won't need to do anything drastic (and using a bladder would require major work - cutting it open, etc).

What's MT, btw?

I was wondering the same thing, then I said it out loud.


Stuff can grow in the pink stuff, algae and whatnot I guess, but only if its diluted. Full strength, no problem with stuff growing in my experience.

But still, no reason to put it in your tank. Boy did I make a mess of things one time when I diluted it to the the bare minimum freeze protection I thought I needed. I ended up with grey/green schmutz growing in all my pipes and all over my tank. What a mess.

Don't forget your hot water loop! You don't want that half full of pink stuff and water, you'll either bust it in a freeze or get algae growing. I disconnect it from the loop, drain it completely, but I also bypass it such that I can pump the pink stuff to all the hot water hoses, faucets, etc too.

[antoha]

That's what I thought at first, but was wondering how an MT bilge would communicate with an MT tank should there be a crack there...

Hot water etc: yes, I now made a permanent T with 2 valves before the pump: one for the tank, the other for the winterizing hose; it's a preliminary version so I took no photos. My pump actually doesn't prime too well, so it used to be a real nightmare starting it after draining the tank fully - I'd need to overfill it and the column of water to the filling fitting would be what made it catch eventually. No more of that, finally!

So the pink stuff in the tank was just from the winterizing loop directly, just flushing the pickup hose+pipe.

Agree though that vodka would work better. Next year!

[zboss]

Originally Posted by antoha

Thank you all! Will do the washing as suggested.

I'm still hoping I won't need to do anything drastic (and using a bladder would require major work - cutting it open, etc).

What's MT, btw?

Why would a bladder require you to cut it open? Ours could probably fit through the 2" fill port.

If you really want to keep it clean rather than put a bag in it, you may want to see if you can rent or buy one of these... we used to use them to clean and sanitize tanks. I surprised they are uncommon in the industry given that you could use the high pressure pump from your water maker:

http://www.tankjet.com/products/tanks_5.asp#15498

[antoha]

The tank is 4-5' deep, and the pickup is a metal pipe going all the way to the bottom. It may even be attached to the bottom. This means that even if I managed to get the bladder in, I would still need another pickup.

Also what I didn't mention is that it's only half of the tank: it's baffled and the fill is connected to the other compartment; they are connected by small holes on the bottom, I believe. The other side also has an inspection port, but so far I couldn't get it open.

I will look into pressure washing too, thank you!

[zboss]

Originally Posted by antoha

The tank is 4-5' deep, and the pickup is a metal pipe going all the way to the bottom. It may even be attached to the bottom. This means that even if I managed to get the bladder in, I would still need another pickup.

Also what I didn't mention is that it's only half of the tank: it's baffled and the fill is connected to the other compartment; they are connected by small holes on the bottom, I believe. The other side also has an inspection port, but so far I couldn't get it open.

I will look into pressure washing too, thank you!

Ah, I see. We have a similar problem with a baffle between two halves of one of our tanks. Our tanks are also fiberglass, were made outside of the hull and then tabbed in when they were installed. The other half of our large tank is also hidden by the baffle and there is no inspection port on that side. Like you, we have no idea what condition the other half of the tank is in. Unlike you we could actually cut the tank out without too much issue.

Some folks that have fiberglass tanks have indicated they are concerned about the chemicals used to make or line the tanks 25 or 30 years ago and ask if there is a chance they are leaching into the water. Which is why I offered the bladder idea.

In our case, we would just use two bladders, one of each side of the baffle with two pick up tubes and a selector valve. The tubes just go from the top of the bladder. As the bladder shrinks the top of the bladder collapses, keeping the pick up in contact with the contents. We could cut a hole as large as needed to put the bladder in and then periodically be able to take it out for inspection and cleaning.