Spring fed in ground concrete pool

I need help. We have a 90 year old in ground concrete swimming pool which measures 50 x 20 and depth is 4 1/2 feet which drops to 10 feet. There is a lot of water. The pool is fed by a spring. Maintenance has been drain pool in the spring and clean the sides with a power washer. We then fill the pool and I would every few days depending on the use toss in about 4 cups of granulated chlorine and would have clear water.
This year for some reason the water is cloudy with algae and I have tested the pool for the first time ever in 40 years of living at the farm. Showing all items ph, chlorine, stabilizers high.

I don’t know if the product (chlorine I am using is different. I tried a product to remove algae and waited 24 hours nothing. I tried a flocculant (SP) and nothing. I know this pool has a lot of water as most of the pool is close to 10 feet deep. It doesn’t really have a shallow because as I understand it, it was built when the children in the family were teenagers and good swimmers.

There is no pump. There is a pipe intake that can be diverted to the pond. My husband has refused to install a filtering system.

The only information I find online are very large spring fed pools in Austin, Texas and a few other locations in the US. Lots about organic pool which this is not.

Any information you can give would help. I realize this is unusual but John had responded to someone about pool and seemed very knowledgeable.

I would like to have this issue resolved because local township and city pools are closed and our grandchildren, children and their friends know and use the pool.

Blessings and prayers for everyone’s safety at this time.

How do you empty it? If you have spring water going through it as opposed to being put in and stagnating, then you could just live with the stuff that go with it. If it is water just sitting there and there is no pump or filtration you would have to put in so many chemicals in quantity that it wouldn’t be very nice to swim in.
My grandparents dammed a burn years ago to make a swimming pool, it was just dug out with a tractor, no concrete except on the actual dam, and it was full of beasties algae etc but nobody cared.

Hi Frannie,

If this is the first time the problem has arisen in 40 years, then it would tend to indicate a change in the quality of the water being fed into the pool perhaps.
Might be a good idea to have a stroll upstream if that is possible and see what has changed.
You could try a repeat of the draining / cleaning/ refilling process, but if the problem persists then it may well come to having to install some sort of pumped filtration and treatment system.