by Kayla
(Kingston, MA)

I have a saltwater pool and it is such a dark color green I can't see the bottom anywhere. I put a little bit of salt in the other day and that helped a little bit but almost barely noticeable.

I have been dealing with green water since I installed the pool in about May. I have had a pool before and have never had so many problems as I do now. I have tried everything the water test has recommended and nothing has helped at all. The other day I shocked it and I watched the water turn an even darker shade of green in about 20 minutes.

I am hoping you can fix this or give me some advice to start to fix this mess.

Here are my stats:
CYA: 94
Tot. Chlorine: 1
Free Chlorine: 1
pH: 7.5
Tot. Alkalinity: 105
Adj. Tot. Alkalinity: 77
Tot. Hardness: 82
Minerals: 2500
Borates: 31
Copper: 0

This is what I was recommended to buy:
93 lbs Mineral Springs Beginnings
1 lb Balance Pak 100
0.25 lbs Lo 'N Slo
24.25 lbs Balance Pak 300

I am so upset and frustrated and I don't know what to do anymore please help me!

Thanks for the question Kayla

Yes I can help and you may not need what your pool store recommended, so here we go. We'll start with what was recommended to fix your problem.

This is what I was recommended to buy:
93 lbs Mineral Springs Beginnings - this is nothing more than regular pool salt. You might be able to get it cheaper somewhere else. Here are some links to help with that. If you have a local feed store, check with them. I got the Y salt pool from our feed store. Just be sure the salt you use is a FOOD grade salt. Very important.

1 lb Balance Pak 100 - sodium bicarb which is the same thing as baking soda. Get some Arm & Hammer or a generic brand from the grocery store for 1/3 the price.

0.25 lbs Lo 'N Slo - Sodium bisulfate a.k.a pH and alkalinity reducer. Muriatic acid is the same, although a bit more dangerous. See which one is cheaper.

24.25 lbs Balance Pak 300 - calcium. If you have a plaster pool it would be good to have the hardness between 150 - 250ppm, otherwise you're wasting your money. If you have a vinyl pool, forget about the calcium. The only function calcium serves in your pool is to prevent the leeching of calcium carbonate from the walls of concrete, plaster or tiled pools. Regular calcium chloride will do the job so don't overpay for something that has colorful or flashy markings on the container. Just ask for normal, average,
everyday, run-of-the-mill, no frills and nothing fancy calcium chloride.

Now for the fun part. I can tell you exactly why your pool is green and why the chlorine won't hold. The pH and total alkalinity (TA) are fine, but the CYA/stabilizer is much too high. There's a CYA/chlorine relationship that needs to be met, and this is what many pool store employees don't know or understand.

The chlorine is 7.5% of your CYA and that's 30 - 50ppm. As the CYA increases the chlorine level must increase to keep this relationship. To have a CYA of 94ppm you'll need to keep the chlorine level at 7ppm.

Your chlorine is inactive and causing the algae because of the higher CYA. To keep the chlorine level at 7ppm will require alot of chlorine, something that you probably don't want to do.

The remedy is this - you need to do a partial drain and refill, I would say about a 2/3 drain and refill. There's no easy way to reduce the CYA and no chemical. A water change is needed. By doing a 2/3 drain and refill you will, in effect, reduce the 94ppm CYA down to about 30ppm, which is in the right range of 30 - 50ppm.

You can dump 100 gallons of chlorine in the pool, and spend thousands of $ on algaecides, flocs, and clarifiers, and it may clear it up for a little while, but I can almost guarantee your pool will turn green again for the reasons stated. I've been doing pools, and cleared up hundreds, since 1999 and have seen this many times.

Once you do a partial drain and refill, it will be time to re-balance the chemicals. I strongly suggest taking the readings on the fill water. This way you know what's going into the pool. If the TA of the fill water is 200ppm, there won't be any surprises because you'll know the TA needs to come down to 80 - 100ppm. Same with the pH and hardness.

I have no idea what the readings will be once you do a 2/3 drain and refill. When you get to this stage you can email back and we can go from there. The pH might be very high or low, along with the hardness and alkalinity. After the refill, allow the filter to run for 24 hours, then do a full test on the water. This will show what course of action to take. Please don't get "pool stored".

If you would like personal assistance, I do phone consultations for a donation of your choice. It makes things go much faster. If you choose to not go that route, we can correspond by email.

Contact Me


Hope this helps and have a great Summer.


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