Water tank slime

[GibseaRob]

I have a Vetus 100 ltr water tank that has developed a brown slimey coating on the inside. I have soaked it several times (for periods up to 24hrs) with imperial quantities of PuriClean and seem unable to shift the muck, although the water now runs clear, albeit with a quite chlorific smell... Any suggestions as to how to remove the slime?

 

[vyv_cox]

There's only one way - mechanically. I added a second inspection hatch to my bunk-length tank so that I could brush it throughout its length. We had tried all the commercial additives, plus Milton and bleach, but nothing touched it. Recently we have been cleaning a 200 litre bag and found the same thing. A length of plastic pipe with a rag tie-wrapped to one end fixed it in no time.

 

[Dipper]

Like you, I found the brown slime wouldn't shift from the inside of my Vetus flexible water tank. In the end I cleaned it by putting a little sharp sand in plus some water and sloshing it all about. I'm not sure how often I could do that before I caused too much damage but it doesn't seem to have harmed it so far.

 

[GibseaRob]

Thanks, I'll try scraping as much out as much as possibe first, then move onto the sand. I'll post the results once I am enjoying a fresh cup of tea.

 

[Modulation]

There's only one way - mechanically. I added a second inspection hatch to my bunk-length tank so that I could brush it throughout its length. We had tried all the commercial additives, plus Milton and bleach, but nothing touched it. Recently we have been cleaning a 200 litre bag and found the same thing. A length of plastic pipe with a rag tie-wrapped to one end fixed it in no time.

+1
But I think that the problem is more to with perception than reality. If you have used Puriclean or Milton correctly (important that you fill right up to the brim of the filler tube and leave for long enough) then you will have killed all the nasties - even those which "live" in the slime. Inert slime itself isn't a health hazard - Reservoirs are full of the stuff and we don't all drink bottled water from highland springs. And even if you do clean out your tank you're still left with the insides of all the distribution pipework.
The chemical smell tends to go after a couple of fillings.
The problem is convincing my wife of this!!

 

[jimbaerselman]

There's only one way - mechanically. I added a second inspection hatch to my bunk-length tank so that I could brush it throughout its length.

Me too.

The slime arises only if some light gets into the tank. Enough light can be transmitted through a light coloured GRP hull. Hence all decent water storage tanks are light proof (often black plastics).

The free chlorine from hypochlorites will kill all bugs effectively - a powerful oxidant. Plain bleach (without "thickeners") is much cheaper than Milton (a very dilute and expensive hypochlorite). Silver salts and iodides also do the job, but rather more expensively. If you can just smell the chlorine, it's effective. To remove excess smell, add some acid. Vinegar is fine. The chlorine will then go out of solution and the smell disappear. Flush and re-fill . . .

 

[Georgio]

Have had the same slime build up in a vetus 100L tank, the only answer was a stick with a ball of cloth on the end then lots of rinsing.

Build up was probably my own fault for not using the tank often enough.

Regularly used and topped up water tanks don't seem to suffer.

 

[Blueboatman]

If you can get the end of a hosepipe through the inspection hatch, with a high pressure spray fitting on the end, just wiggle and poke it around and then mop out the residue with a rag/hand pump. tedious though