New to Pool Care - To Slam or Not to Slam?

[TRT77]

I am new to posting, but have been doing lots of reading. I started my own pool care a week ago. I have an 18,000 gallon in ground chlorine pool. After canceling my pool service, I bought a Taylor K2005 test kit and went to work. After draining 3' of water out of my pool due to high conditioner and CH levels, I finally got everything in balance. However, I have algae growing in several areas and seem to have sand on the bottom which I'm thinking may be algae as well. I broke down my DE filter last weekend and cleaned and inspected all the panels. No rips or tears, so there should be no DE coming back into the pool. And I haven't seen any coming through the jets. So now that my water is clear (way more so than when my pool guy was doing it), I need to get this algae gone. I'm going to test now and will post my levels shortly.

Any feedback is greatly appreciated!

Just tested my levels and they are as follows:
FC - 2ppm
TC - 2ppm
CC - 0ppm

PH 7.8
TA 80ppm
CH 320ppm
CYA 40ppm

I can't seem to maintain chlorine levels. I tested chlorine on Thursday evening and CC was 0, just like now. I added a 3" tablet to the skimmer basket and one to the floater. As well as adding 120 oz of bleach per the pool calculator. We left town that night, so no one has been in the pool. We returned home yesterday and this morning was the first time I've tested it. So, after a few days, my chlorine is back down again.

 

[pooldv]

Welcome to TFP!

Yes, SLAM. Your FC is below minimum. This allows algae to grow which is now consuming more chlorine. It is only going to get worse.

Chlorine is set based on CYA and Chlorine CYA Chart. FC should always be at target or slightly higher and never below minimum.

Pool School - SLAM - Shock Level And Maintain
Pool School - ABCs of Pool Water Chemistry

BTW, pucks add CYA, Pool School - How to Chlorinate Your Pool

also, add your pool info to your signature as shown here, Pool School - Getting Started

 

[Texas Splash]

Another Lone Star member ... welcome! You already received your initial advice, so stick with it and let us know if you have any more questions. Remember, a SLAM is not an overnight process, so be prepared for a few days of constant FC testing and brushing. You'll get it. Welcome!

 

[Richard320]

Welcome!

The first part of the SLAM is Shock Level. For 40 CYA, that's 16 FC. Your K-2005 can't measure that high. To turn it inmto a K-2006, order the FAS-DPD test. There's no other way to accurately measure FC at the levels you need.

If there's a lot of algae, it will all disappear pretty quickly. That the second half of SLAM: And Maintain. There's the rub. You don't know how much is left unless you let FC drop well below 5 so you can read it, and then you have to go back up to 16 FC. Get the test kit coming and fumble through as well as you can. Frequent and thorough brushing will speed it along. Algae develops a slimy biofilm scab that protects it from chlorine, so you need to brush it off so the chlorine can kill it.