My Pool Has A Green Tint To It

by Jason Millan
(NYC)



My pool has a green tint to it on the deep end my pool is 75,000 gallons. I was wondering how much should I add, it's a powder shock.


The levels are
CH:3.0
ph:7.2
TA: 110
Calcium hardness:60




Thanks for the question Jason

First I would ask if you have a plaster or vinyl liner? If it's plaster then you can go ahead and use calcium hypochlorite. You need to raise the hardness up to 150 - 250ppm. One you get there stop using cal. hypo. and go to liquid chlorine. To raise the hardness a bit faster, you can use calcium chloride. It's 1 1/4 lbs. per 10,000 gallons to raise the CH 10ppm. If it's a vinyl liner just leave the hardness at 60ppm. CH is more important for plaster than vinyl.

next is the CYA/stabilizer. I don't have that and Without that number it's impossible to tell you to shock or drain some water. If the CYA is high, above 70 - 80ppm you'll need to drain about 2/3 of the water, refill, FILTER for 24 hours, retest everything, then shock. There's no chemical to reduce the CYA.

If the CYA is too low, below 20ppm, you'll need to use Dichlor chlorine. This is a stabilized form of chlorine. Once you reach the 30 - 40ppm mark, stop with Dichlor and go to shocking with regular liquid chlorine.

Be careful when using Dichlor as it can get out of hand quickly. For every 10ppm of chlorine added with Dichlor, you'll raise the CYA by 9ppm. For every 10ppm of chlorine added with Trichlor tabs you'll raise the CYA by 6ppm.

You can find the chart you need right here:

Swimming Pool Chlorine

It's 3 1/4 qrts. of liquid to shock per 10,000 gallons and 1 1/4 lbs. of granular chlorine per 10,000 gallons. That come out to 6.5 gallons of liquid chlorine or 10 lbs. of calcium hypochlorite.

Shocking is a process, not an event. The trick is to get AND keep the chlorine above 10 - 12ppm for a period of time. You'll need to manually dose the pool with chlorine to keep it at 10 - 12ppm. Make the adjustment at night, then retest in the morning. Be sure to have the pump running 24/7 and backwash once per day. You can go up to 15ppm, but no higher. Anything after that and you're wasting money and chemicals.

You'll know this is working because the pool will go from green to a white/grey cloudy and the chlorine will begin to hold better. First you may lose most, then 2/3, then 1/2, and so on. Once you only lose 1 - 2ppm of chlorine 8 - 10 hours after the last application you know the algae is dead. Now it's just a matter of filtering and backwashing once per day. Broadcast the chlorine around the perimeter of the pool and brush well. This will loosen up any algae adhering to the walls and bottom.

If it's an emerald clear green it could mean metals in the water. You can get this after shocking with a hypochlorite source of chlorine try to raise the pH and it turns green. If this happens it's usually a sign of metals in the water.

Using an algaecide with copper in it and high chlorine or pH levels can make it turn a clear emerald green. Lower the pH using muriatic acid.

This should cause the water to fade to confirm that there's metal in the water. Add a metal sequestrant.

Metal in the water, mainly copper and iron, might turn the water green after adding chlorine.

To post a reply, or if you have a similar question, you can see your post on the Q&A page in the "Algae/Green Pool Water" category.

Check back to this post for updates or answers.

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Hope this helps and have a great Summer.

Robert

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