Cloudy Water

[iamnos]

First, big thanks to the group. This is our first season with our pool, been up and running almost two months using the TFP method and loving it.

Thursday (3 days ago), we got a very heavy downpour in the morning, and even though the pool decking is sloped away from the pool, we still got some dirt that washed in. Since then, we've vacuumed a few times, I've backwashed the filter twice. On Saturday morning, there was a fair bit of extra dirt on the bottom, but sucked all that up. Levels have all been fine, but we are using more chlorine than usual. Normally we've been losing around 0.5-1.0 ppm in a 24 hour period. Now it's over 2.


Levels early today:
FC - 3.0
CC - 0.0
pH - 7.5
CYA 35
TA - 120
CH - 130

I added enough chlorine to bring it up to 5.5.
Checked a couple hours later and it was around 4 or 4.5. I added about another 1.0ppm worth.

Normally I run the pump about 4 hours a day which should be enough to turn the water over once. Thinking maybe I should run it longer to help filter out all the dirt that came in. Or maybe I should let the pump finish its current cycle, sit for a few hours and see if more settles out?

Thanks for any advice folks.

 

[ajw22]

Target for CYA 40 is 5-7. I would bring FC up to high end of the range.

Sand filters are slow to filter so I would run your pump a lot more until the water is clear.

 

[iamnos]

I'm keeping the chlorine up, and left the pump run for about 20 hours straight. After it was off for an hour or two, still had settling of some dirt. Kids are in it now, but I think I'll leave the pump off for a bit, let everything settle, and then vacuum to waste. The PB didn't really talk about that setting, but after reading up on it online, that seems like the best thing to do at this point. Should dump all that dirt out, and worst case I have top up the pool a bit with fresh water.

 

[iamnos]

So this did turn out to be algae. I looked back at my logs, and realized the pool did dip down below 3ppm, and on top of that we had a lot of dirt in the pool from a storm, followed by a bunch of people over and in the pool.
So, started to SLAM.
CYA: 35 (though I understand you should round up to 40)
Added chlorine to 15ppm and after 4.5 hours it's still holding.
CC so far has been 0 or 0.5. I've vacuumed up a lot of what I presume is dead algae, brownish/green on the bottom, especially edge areas I suspect are low flow areas in the pool.


One quick question, once it passes all three tests, how low does the chlorine need to go before it's okay to swim again. At this CYA, the recommended level is 5-7, do I need to get down to 7?

 

[Fast7]

It's safe to swim at or bellow SLAM level for your CYA, so practically you can still swim in it while SLAMing as long as you don't go over your SLAM target and don't drop bellow minimum.

 

[iamnos]

Yay, passed all three SLAM tests this morning. Water was clear, just a tiny bit of dead algae on the bottom that I vacuumed up (I did a full vacuum of the pool). Water looks fantastic again and didn't even lose any swimming days. Learned a valuable lesson about FC levels, and it only cost me about 7 litres of chlorine (like $7.50).