Algae in water tanks- new 44 DS.

[ctjeanneau]

Another newbie fun challenge, and I need some advice.

Boat is into her first full season and we noticed immediately this spring that we had algae in the filter before the water pump.
Bad enough to clog the pump and require cleaning of the filter. Both tanks are affected but it is much worse on the forward tank.
The water smells fine, we haven't been drinking it but would like to be able to eventually. I tried the Water Shock  from West Marine and it didn't touch the algae situation.

I was going to resort to bleach and hopefully be able to flush it we'll enough later that my wife would not turn blonde after she showered.
Then, after all I do like blondes so I am not sure on that....

Is there a way to flush all lines before the pump , without running the pump? I assume all the sink water and shower water drain goes into my holding tanks and if so, makes it impractical to flush a full water system without getting a pump out. Help!

[rene460]

Hi ctjeanneau,

Even when you kill the algae, you still have to flush it out of the tank and out of the rest of the system.  It usually takes two or three tanks full, it is a lot of buckets.  On the hard you may be able to siphon it out, but on the water it has to be pumped out one way or the other.  Can you make a temporary connection to the bilge pump with some suitable hose fittings?  If discharge is not allowed, perhaps a day sitting on the pump out station until you have flushed it through, is an option if even your grey water goes to a holding tank.  The shower and sink pumps are not rated for that continuous duty, and will probably not last the distance.

Once the tanks are empty, if it is possible to get at the inside of the tank, (ours has an inspection hatch in the top), check the inside and clean it out as well as practical.  I would then try putting the full dose of chemical into the tank with only 10 or 20 litres of water then fill the tank after it has had time to work.  Some chemicals recommend 24 hours before draining.   Unfortunately it is then time to drain the tanks again.  Second time chemical added by the same process and flush out all pipes including the stern shower as you pump it out.  Remember to cycle the pressure accumulator as part of the process.

I would suggest special purpose chemicals suitable suitable for potable water rather than bleach.  My bleach bottle claims it is suitable, but I always worry about the tank material picking up the flavour.  I assume it means at worst an extra tank flush or two, but would keep it as a last resort.  Perhaps I am too conservative on this.  It will be interesting to see what others think or have tried.

rene460

[rxc]

I am curious why you think that the sink drains go to the holding tank - is there a new regulation that requires this? I think that they do not go to the holding tank, but instead to seacocks and directly overboard.

I have dealt with fresh water problems like this on a previous boat, and found that I needed to treat the tanks again after the bleach treatment, with a chemical that neutralizes the bleach, or else it takes forever to get rid of the chlorine taste. I believe that WM sells this stuff - I still have a bottle on-board. Also, you really do want to flush the bleach thru ALL of your frech water piping, or else it will just grow back. And, make sure that you fill up the tanks to overflowing, so that you treat the vent lines, as well.

It can be a real pain in the neck to treat a big boat water system, but if the admiral is unhappy about the water it is best to catch it early and deal with it.

Do you have any possiblity of getting your dealer to flush it? Delivery of a new boat with algae would sound like a bad commissioning/prep job that they are paid to do....