green colour water

[Guest]

Hi Can you help I have a small salt water pool the problem I have is the P/H is very high colour purple the chlorine level is 2.5 but the water looks green with no algae present the pool walls are not slimy and you can see the floor of the pool. The pool is cement with ceramic tiles.

[chem geek]

If it's a clear green rather than a cloudy green, then it sounds like this could be copper since high pH can precipitate it (as copper hydroxide/oxide/carbonate). Did you use an alagecide that contains copper? You can have the water tested for copper and if it measures high in copper then you can use a metal sequestrant of do partial drain/refill.

[Guest]

Hi thanks for the help. No algaecide has been used and the water is a clear green the pool has metal steps at the deep end.
I have today reduced the P/h by using P/H liquid and the colour has improved a little. The pool also has a winter cover on through the winter months could this aggravate the problem as no light gets through the cover?

[chem geek]

If reducing the pH reduced the color, then this does sound like copper in the water. I don't think the winter cover and lack of light did anything, but at some point you probably got copper in your water. Have your water tested for copper and also have your fill water tested as well (though it's unlikely to have copper -- usually iron is more of a fill water issue). If it tests high for copper, then first lower the pH to try and get the copper back in solution (and not green) and then use a metal sequestrant. If your fill water doesn't have copper, then a partial drain/refill would also reduce the copper level. Of course, that doesn't tell you where the copper came from in the first place. Has anything acidic been added to the skimmer such as Trichlor tabs? That could have stripped copper from the heat exchanger in a gas heater, for example.

Richard

[fatybabe]

As Chemgeek said reduce your pH levels in pool so Copper holds back in solution.

Another approach to using sequestrants which is applied is to increase your SI within your pipings (Soda Ash) before return water reaches your filter, you will be looking at around + 0.5 to + 0.7 that way copper precipitates to filter - back washign should be done after 24 hrs and repeated if necessary.

However i wont recommend you do this if you are unfamiliar with control of water possible side effects would be scaling and caking of filter.

[fatybabe]

I mean i wont recommend you do this in the long run...... these are common technniques in waste water treatment and can be applied tos ome extent in pools.

It is also the least expensive method of approach, but can pose some difficulties to you.