Paint inside of water tank

[mattnj]

I have searched the forum and not much came up...so here goes...

Inside of GRP water tank is "manky" spots of black mould and what looks like perhaps osmosis type blisters perhaps....can I "just" sand it back and paint with something (2 pack epoxy perhaps?) or is it more complicated than that?

Is there products for water tanks? I went into Chandlery and they gave me a blank look, like I was a bit mad

Tank is about 300l shaped to hull and bonded in, so its not going to be replaced anytime soon.

 

[macd]

Sanding back and painting with epoxy makes perfect sense, but you're best advised to use an epoxy which is food/water safe. This isn't an especilly onerous or expensive property: just a matter of reading date/safety sheets or, easier still, asking a specialist epoxy supplier. In the latter category would not be any chandlery you're ever likely to encouter, as you have found. Google is your friend.

 

[pvb]

It's going to be almost impossible to do the job properly. I'd settle for cleaning out carefully, then using bleach to kill any nasties, fill/empty rinse a few times, then just use it (adding purifying tablets each time you fill up).

 

[neil1967]

We had something similar in our tanks (2 x 500 litre), when we bought our yacht, plus many years of accumulated sand and limescale. We lifted handfulls of sand, grit, scale etc out, scrubbed the tanks out with strong milton and then filled up with weaker milton before flushing through. That was a couple of years ago, and all still seems OK.

Neil

 

[lumphammer]

I had similar problem with one of our Moody water tanks. After cleaning out I used Scotchkote 165PW Urethane Coating from Promain.co.uk. It is a 2 part paint, water safe and very gloopy. One coat seemed to cover really well. The bit I peeled off the roller tray was about half a mm thick and I could bend it around 180 deg and it doesn't tear, Quite expensive at about £52 + VAT for 2L tin. I needed tin and a half for a 30 gal tank.

 

[AndrewB]

I have been using an Australian product intended for water tanks: Altex AltraShield 2000 polyamide epoxy but specifically with Altex X-100 thinner to ensure it is food-safe (see http://www.altexcoatings.co.nz/vdb/document/247).