Test results, bleach and muriatic acid recommendations?

Started the water exchange today. Gonna shoot for 50% drain or so then check CYA level. What would be an acceptable target for CYA given my numbers from a couple days ago?
You should target a CYA of 50 ppm. So about a 60% water exchange.
 
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Update: ran water exchange for about 12 hours, which should have been over 60%. Ran pump for an hour then tested CYA and it was down to 80pm (from 120). Draining more today to get to 50ppm.

I have not been adding chlorine for a few days while doing the drain. This morning I noticed some yellow powdery spots on the plaster on the side of the pool that gets the most shade. I brushed and it poofed/clouded and came off easily. Thinking this may be mustard algae? Would you recommend SLAMing the pool once I get CYA to 50? A little concerned about the yellow-y substance. I had seen it once before in the last few weeks. (thinking high CYA and not enough FC allowed algae growth). Water is clear and no other issues, but I'm sure FC is low very low due to exchange. Thanks
 
Yellow algae is really rare.
Keep FC in the pool water while doing your exchange. Add liquid chlorine to the incoming stream.

You will want to follow the SLAM Process once your exchange is done.
 
It is most likely algae, or dust. Were it collects is based on the circulation pattern of the water in the pool.
 
Okay just tested CYA using the diluted method, it was about mid-way between 20-30 lines on the viewing tube. So I am somewhere between 40-60ppm (yay). Going to start SLAMing. Thanks for the help so far, any tips on SLAMing for the first time other than is what is on the site?
 

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Okay as of 8am this morning FC still at 20ppm, CC= 0.5 and water is clear. I tested CYA after pump ran all night so water should be better mixed and found it to be 70. My previous sample must have been more fill water than pool water even though I drew water from the middle of the pool. I brushed the whole pool and bumped FC up to SLAM level for 70 CYA and will keep it there another 24 hours. Any suggestions?
 
Okay as of 8am this morning FC still at 20ppm, CC= 0.5 and water is clear. I tested CYA after pump ran all night so water should be better mixed and found it to be 70. My previous sample must have been more fill water than pool water even though I drew water from the middle of the pool. I brushed the whole pool and bumped FC up to SLAM level for 70 CYA and will keep it there another 24 hours. Any suggestions?
Also found pressure very high on my filter so backwashing now.
 
Looking back, you said your first exchange ran for 12 hours and you exchanged just over 10000 gallons. I do not find that realistic. Most exchange rates, using a sump pump and water hose, is about 400 gph. So you exchanged maybe 5000 gallons. Your CYA drop from 120 to 80 would verify that amount.
 
Looking back, you said your first exchange ran for 12 hours and you exchanged just over 10000 gallons. I do not find that realistic. Most exchange rates, using a sump pump and water hose, is about 400 gph. So you exchanged maybe 5000 gallons. Your CYA drop from 120 to 80 would verify that amount.
My pump says it can do about 1200 gph at a height of 10'. I have no way to verify that, but the garden hose at fully open seemed to about match it in terms of incoming water to outgoing. Ran exchange for two sessions, first day 12 hours, second day about 6 hours.
 
Did you measure how much the sump pump was actually pumping by measuring it? I use a 5 gallon bucket and time it. Never get more than 7 gpm.
 
My sump pump is a 1/2 hp. The smaller ones pump even less. The rate they state is very overstated (0 backpressure). If you use a common garden hose from the sump pump, it will not give you much rate.
 
Just an update for anyone interested. Will do more exchange tomorrow but been maintaining water until I have time to setup and watch it for a few hours. Test results:

FC: 9.5
CC: 0
CH: 400
TA: 150
CYA: 80
pH: 7.8

Added some muriatic acid. I know CYA is outside recommended range, TA is a bit high, everything else seems okay to me. Any feedback?

Thanks!
 
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