Algae keeps coming back

[TerriP]

Upon opening the pool this season, we SLAMmed successfully. After a few weeks an algae bloom generated from our wedding cake stairs. We removed those and successfully SLAMmed again. For several weeks the pool water was clear, then a little cloudy. Now, seeing algae on the bottom of the pool again.

We have a Hayward cartridge filter. I have 2 cartridges and I swap out the dirty for clean when the pressure increase past 20 and at the first sign of cloudiness. FC has been maintained between 3-5.

I think the recurrence of algae is coming from the cartridges never truly being free from algae. How can I treat/clean the cartridges to make sure I an not reintroducing a problem each time I switch one out?

Current numbers:

FC = 3.0
CC = 1.0
pH = jumped today about 8.2

Ready to SLAM and add muriatic acid.

Is a different filter system the answer?

Not using the Nature2Vision Pro sanitizer currently.

 

[harleysilo]

What's your CYA level?

 

[lightingguy]

If you are slamming correctly and keeping your FC/CYA ratio correct then the cartridges wouldn't be too much of an issue.

What's your cya level?

 

[buzzard302]

The last two summers, I struggled with recurring algae on the walls and steps. I was even maintaining the highest FC level for my given CYA level. I would brush it constantly, perform SLAM's, pull out the light, etc. etc. This summer, I have not had one hint of algae in the pool. It has made me lazy about brushing the walls to be honest.

The only thing I did was get a new cartridge from Amazon. I tried a Pleatco Advanced brand this time around. The filter media feels a bit different than an old Pleatco and Unicel that I had. And the Pleatco Advanced is so much easier to clean with a hose. I would advise that you SLAM first if you do decide to change your filter.

I'm not saying it's the magic fix, but if you might need a new cartridge anyway, it was worth the 40 dollars for me.

 

[PAGirl]

How long are you running the pump? Do you have good circulation around the steps? Mine are on the opposite side from the return, so I periodically pour a little bleach behind them (not wedding cake type, so there is a gap between the pool wall and the steps) and swish it around under and behind the steps. If your CYA is above 40, then you are not staying above the minimum FC and algae can occurr.

 

[duraleigh]

Filtration has virtually nothing to do with the presence of live algae. Chlorine kills it. A new cartridge will not.

Post your CYA number but algae forms when the chlorine is too low and is killed when the chlorine is adequate for your CYA.

 

[domct203]

Filtration has virtually nothing to do with the presence of live algae. Chlorine kills it. A new cartridge will not.

Post your CYA number but algae forms when the chlorine is too low and is killed when the chlorine is adequate for your CYA.

Agreed.

If you completed a SLAM by meeting all 3 criteria, all algae in the water should be dead, filter included. You are most likely letting your FC get too low.

 

[TerriP]

Checked the CYA last week and it was at 45. Now I am out of that solution in the TF100 kit. Waiting for new one to arrive.

I took the stairs out weeks ago.


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[domct203]

Checked the CYA last week and it was at 45. Now I am out of that solution in the TF100 kit. Waiting for new one to arrive.

I took the stairs out weeks ago.


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Round up the CYA to 50ppm, and your minimum FC is 4ppm. Letting your pool go close to and below 4ppm (your OP shows FC 3.0ppm) is allowing algae to reproduce fast enough to overtake the low level of chlorine. The FC target for your CYA is 6ppm.

I recommend that you try a FC of 6ppm as your minimum, with a target FC of 8ppm.

Are you currently SLAMming at a FC of 20ppm?

 

[TerriP]

I was slamming to 16. For the future I'll keep FC about 6


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