Well weather so far this spring early summer has been OK in the UK.
I use a separate water holding facility which is filled with tap water ,
dechlor added and then aerated 24/7. I seeded the facilty at start-up with
gunge from the pond filter. I'm always expanding it as my pond fish load
increases,and my water changes rise. Time to build a new pond:-)
What I have noticed is that as the facilty ages and there is a bigger build
up of grey|black gunge on the sides the less the pea soup affect following
fill up.
I find the reverse to you I can add pea soup conditioned water from the
facilty to the pond, it clouds the pond slightly and clears in less than a
day. The fish love the murky introduced water; presumably infusoria and
stuff like that! And I'm doing 10% to 15% water changes.
One could grow floaters in the facility which would tend to reduce nitrates.
My guess is that your pond doesn't have enough veggy filtartion if a top up
load is resulting in pea soup? How long does it last before it clears; if
it's a short period of time then maybe you should just accept it.
Roddy



"Conrad" wrote in message
...
Hello

I have to occassionally top up my pond (2500 gallons when full) - not,
I hope, due to leaks but evaporation - yes, we do sometimes get hot
weather in the UK.

Anyway when I top up the pond I always get a "green water " problem
shortly afterwards. I use tap water as I do not trust run-off rain
water from the various downpipes in case there is some chemical
contamination from the roof materials. I'm pretty sure it is the
nitrates in the water that's causing the green water in the pond and
would like to find a way to treat and store top-up water.

I have thought about dumping a load of algae/blanket weed in the water
in the hope it will use up the available "food", die off and leave the
water more suitable for topping up the pond.

Has anyone any ideas on this or can suggest some other way to treat
the water, preferably not with chemicals but if it's the only way I'll
give it try.

Thanks in advance for any help.

Conrad