Help - Pool Dark Green and not improving

[Steph1]

Hi

We have a 10 x 5 pool with an abri, we were away for a few weeks in the winter and the pump must have tripped out. When we returned the pool was very green. We opened it up last week, drained 2/3 rds of the water out and refilled it. We have chlore chocked it and used 10 litres of anti algues and it is still very dark green. The ph is high and although we have added ph minus it has made no difference, it is also not showing any chlorine. We have the pump on 24 hours. Any suggestions would be gratefully appreciated. Thanks.

Steph1

[Poolguy]

Yes That sounds like a bad case of green pool.

There are a number of things, which can be done, but first we must establish the base.

If your pH is high then that is the first thing to deal with. I would imagine that this is because you are in a hard water area. You must test using phenol red tabs and get a reading. If its above 7.6 then you'll need to lower it before anything else. I suggest that the most effective method is to go down to the Brico and get 5 litres of Hydrochloric acid concentrate, it should cost you about 5-6€, then mix it with water at a rate of 5 litres of water to 1 litre of acid - be sure to add acid to water and not the other way around. Introduce that to your water carefully and spread evenly. Wear rubber gloves and goggles for your eyes as a precaution.

Then test for chlorine using DPD1 tablets. If you have none showing then you'll need to choc again. GO down the Supermarket and buy Eau d Javel concentrate 9.6% in the 200ml satchels, about 0.25€ each. Buy about 10 off they will always be useful. Mix the Javel in a bucket of water and pour it into the pool walking briskley forward, don't spill either the acid or the Javel on the liner or on the margelles otherwise it will do damage. Keep doing this until the level of chlorine is 'off the scale' and then keep circulating for a couple of days. That should clear up the algae problem eventually.

Don't use any more antialgae as its already too late and the copper concentration of the pool will go up to dangerous levels. Don't use Peroxide or any other products as they are very harmful. If you still have problems then call me and I will arrange a visit for a comprehensive water test. It is possible that you have too much cyanuric acid concentration in the water, which is inhibiting the chlorine from doing any work.

I would urge you to think about an automatic sanitising system so that your pool will be maintained even when you are not there which will avoid a recurrence of the 'green nightmare'.

PM me if you need more help

 

Andrew