phideaux_2003 said:

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I've got green algae in my hot tub (has yet to migrate to the pool, but that's not far off...) Things I've done:

-Really good chlorine tablets with algicide in them is my normal stuff and it's topped off

-Cleaned out filter grids and replaced DE

-Clorox brand pool shock/algicide

-No Mor Problems brand water clarifier and algicide

-Constant brushing with nylon brush and now brushing with stainless bristle brush

I just cannot get this stuff to go away.

What's the nuclear option?? I want to get it right before we start getting in it for the summer.

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Chlorine tablet raises the cyanuric acid level which makes your chlorine ineffective. It doesn't matter how much chlorine you use, it will still grow algae. Only thing you can do to lower the cyanuric acid level is to replace the water.

Read this website https://www.troublefreepool.com/blog/

What Martin stated is correct. Your CYA level is too high. Drain some water to get the CYA to a manageable level and bring your chlorine to shock level using liquid chlorine. You have to maintain shock level until you do not lose any chlorine levels overnight.

Using pucks slowly increases your CYA until chlorine is ineffective (chlorine lock). If you continue to use pucks, you just have to be diligent in watching your CYA levels and drain your pool from time to time.

I couldn't get rid of algae before. Then I stopped using tablets and/or pucks and started using just liquid chlorine . No algae anymore.

+1 for the trouble free pool method. Messed around with all the Leslie stuff last season learning with my first pool. Got it into significantly better shape than it was when we purchased.

As a learned more and tested more accurately, I figured out the cya problem. Kept chlorine high with liquid chlorine over the off season and water looks great. But knew my cya was 100.

Drained about 60% a few weeks ago and no have the cya at around 40. Going to follow the tfp method this year. Actually just ordered a automated liquid chlorine dispenser today.

Another vote for trouble free pool. The pucks will mess you up in no time, with CYA levels constantly on the rise and needing to drain down water to get it diluted out. And in the meantime, as your CYA levels rise, the chlorine in the water is becoming less and less effective. It's a vicious cycle.

Of course, pool service companies will laugh at you if you talk about trouble free pool, or liquid chlorine. Why? It isn't compatible with their business model, despite it being a superior system. They make money by stopping by once a week, brushing for a few minutes, and topping off the puck feeder. It's easy. The use of liquid chlorine requires near-daily testing and small additions of liquid to keep the pool in the ideal range. Spending 5-10 minutes a day can save you lots of money in the long run, and also result in a much cleaner pool.

Regarding pool store testing... Leslie's, etc... that is not recommended either. Their tests have been shown to be wildly inaccurate (especially the digital meters). Many tales out there of folks taking water samples collected on the same day to different stores and getting wildly different readings. You need to get a good test kit (Taylor K-2006C is what I use) and do the most basic tests (pH and free chlorine) near daily. You can go out a bit longer on other items such as total alkalinity, and even longer still on CYA (especially if you aren't jacking it up with pucks) and calcium hardness.

Regarding algaecides and other "pool store" chemicals that usually come highly recommended when you get your water tested... don't go there either. You especially want to stay away from anything with copper or other metals. Metals will build up in the pool, and just like CYA, you aren't getting it out without draining down. Copper buildup is also the cause of blonde hair getting turned green (used to be blamed on "too much chlorine").