Green Pool Issues!!

by Nichole

My pool is 10,000 gal.. after turning green we purchased a shock treatment called green to blue..cleared up the green but still very cloudy and green tinted..these are my current readings-

total alkalinity 330
total hardness 500
cyanuric acid doesn't register a reading so must be too low
ph 7.8 which is highest on my tester so maybe higher
chlorine/bromine 3-6

Don't know what to do or add at this point! ready to drain and start over!

Thanks for the question Nichole

The calcium hardness (CH) is just a bit high at 500. The proper range is 150 - 250ppm. I'd watch that as this can cause a calcium ring at the water line. I don't know the CH of your fill water but you may want to do a partial drain and refill if you have softer fill water. This would be the only reason to do so. If you're chlorinating with granular chlorine (calcium hypochlorite) you must stop immediately. This is not only raising the hardness but adding to the high pH level.

Next is the Green to Blue. This is aluminium chloride and to the best of my knowledge is not the best stuff in the world. This acts as a coagulant which means it binds the particles together to get backwashed out but doesn't kill already existing algae. It binds what it can but then more algae reproduces then you need more product to bind what just reproduced. You can get into a vicious cycle that you may not be able to win.

Then you have no CYA. This is the stabilizer and needs to be 30 - 50ppm. The TA and pH are a bit high which renders what chlorine you have very ineffective.

Here's what I would do. First is to get the TA down to around 100ppm. Use 25 oz. of acid per 10,000 gallons to reduce the TA 10ppm. You need to decrease your TA 230ppm to get to 100ppm. Because you have such a large adjustment to make you're going to need patience and alot of acid.

Add the acid at arm's length in one spot with the pump OFF. Sweep the floor very gently to not allow acid to settle in one area. Allow to sit for 3 - 4 hours then pump back on to FILTER for 10 hours, retest, and make another adjustment. Start with about 50 oz. of acid then work from there.

The acid may have an affect on the pH but not to worry. You want the pH down to around 7.0 - 7.2. Chlorine works better at this level.

Next step is once you have the TA in line it's time to add CYA/stabilizer and shock the pool with
liquid chlorine. You can get granular CYA. It's 1 lb. to raise the CYA 10ppm per 10,000 gallons. If you have no CYA reading, start with 2.5 lbs. Get a large bucket and fill 1/2 with pool water. Add the CYA, mix with a stir stick and broadcast it around the perimeter of the pool and sweep very well with pump on FILTER.

About 2 hours later add liquid chlorine. Same technique as above. It's 1 gallon to shock per 10,000 gallons. Use 1.5 gallons. FILTER for 10 hours then retest the chlorine and CYA. Once you hit the 30ppm mark for the CYA stop using it and keep shocking the pool with chlorine.

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.

At the very end you can use a clarifier to help with the filtration, but not any sooner than that. Triple up on the dose. Normally it's 5 oz. per 5k gallons for maintenance. Use 15 oz. to help get rid of the cloudiness.

Here's a video I did that's similar to your pool situation:

I hope this has answered your question to your satisfaction.

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.

If you feel your situation is more complex and want immediate assistance (within 24 hrs) you can make a donation of your choice and I'll answer your questions by phone.

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Have a great Summer.


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