New maintainer with algae on walls

Ben,

Thank you for following up. I retested the pool at the local store around noon and got the following numbers:

Free Chlorine: 5 (I know it's > 15ppm at this time)
Total Chlorine: 5 (I know it's > 15ppm at this time)
Calcium Hardness: 400
CYA: 120
Total Alkalinity: 150
pH: 8.0
Total Dissolved Solids: 1500

I know the "what would you do" questions are typically subjective to each individual but I'm trying to look long term and determine what is in the best interest of the pool and its maintenance needs going forward. I'm concerned that by finishing out the 70+ lbs of tabs I have that I'll just be compounding my future issues and besides - I can sell the tabs for what I paid for them so I wouldn't be out anything. Couple that with the fact that I have a child who has very sensitive skin; I think it would be best to do a partial drain and get the numbers back down. If I look at this reaslisitcally I'm just whining about doing something that my family is complaininig to me about messing up in the first place... of course I'll never admit that to them - HA!

I'll rent the sump pump tomorrow and get to work. If there is something I'm missing please let me know! Thanks again.

One final question for my own clarification - outside of dilution (and of course rare earth elements that I can't get anyways)... is there any other cost effective way CYA can be lowered in a pool? From my reading I don't believe there is but wanted to ask.

You remove phosphates with lanthanum (a rare earth metal); you can remove cyanuric acid with melamine, an organic base. But, you don't want to do so: it makes a huge mess.

Draining and refilling will put your pool back in service much faster.

Ok - the partial drain is almost complete. On to my next question... since I've got the pool partially drained is there anything I can do to the walls in this state that would be beneficial in combating the algae I had forming on them? Anything else you would recommend I do while the pool is in this state?

If you have any black algae spots, pressure washing them, and then rinsing with bleach would be good. Otherwise, nothing occurs to me.

Ok - partial refill completed this morning. Here are the results from my OTO kit (Taylor K2006 kit not here yet) and my local pool stores tests...

OTO test:
Chlorine: 6 (single dilution method)
Alkalinity: 130
pH: 7.8
CYA: < 30 (the tube only went to 30 and I could still see the dot albeit faintly - my best guess is 20-25 CYA)

LPS test:
Free Chlorine: 5
Total Avail Chlorine: 5
Alkalinity: 120
pH: 7.7
CYA: 25
Calcium Hardness: 210
Phosphates: 50

Looks like things are fairly balanced except a slighly low CYA. I'm not quite sure how these numbers are what they are considering the amount of water I drained but both tests (LPS and OTO kit) came up very close. I made sure to get the samples for the tests 6+ inches under the surface of the water. Anything else you can recommend I do prior to opening for a dip?

Also, being I have a lower CYA am I correct in assuming I will need to add bleach/chlorine more often? Thanks again for all your assistance!

Yes, you will probebly have to add chlorine more often, but if you'll test it daily it won't take long for you to determine how often that needs to be.