Can't Clear the Cloud

[Noggin]

Pretty new pool owner here...

Stats yesterday morning
Free Chlorine 5ppm
Total Chlorine 5ppm
Combined Chlorine 0ppm
pH 7.8
Hardness 155ppm
Alkalinity 85ppm
Total Dissolved Solids 1500ppm

15,000 gallon in ground pool, plaster walls, sand filter. Water is cloudy white. Pump seems to move the water quite well when on and the pressure is about 10lbs after a backwash.

Last weekend the guy at the pool store sold me some clarifier and told me to put "this much" in the pool, "this much" being 16 oz. The instructions say to use 3 to 4 oz in a pool of my size on a weekly basis, so I figured that 16oz would be OK. But it got cloudier. About 4 days later with no improvement I decided to floc.

I brought a water sample to the pool store and got the numbers above. I was told to fix the harness first, so I added 10 pounds of Ram hardness control, let the filter run for 4 hours, and then added 12oz of pH plus to get the pH up to around 8. I let the pumps run for another 4 hours and then added 6 lbs of flocc. I set the timer to shut off the pump in 4 hours (as the instructions say) and let the pump run in whirlpool/recirculate (as the pool guy said to do). This was at about 7 PM last night. 12 hours later, the pool is cloudier than it was last night. I can no longer see the pool drain in the deep end (6ft). I think I'm supposed to wait 24 hours before vacuuming, but I was really hoping to see some results this morning.

If this is algae, will the flocc help? Can algae even make the pool water cloudy white? Should I have let the pump run longer? I think I'm going to start adding some DE to the filter to get better filtration, but I'd like to try to get the water clear first.

[Noggin]

How obvious should the flocculated stuff be on the bottom of the pool? I just looked into the shallow end and saw a tiny amount of black stuff on the bottom, but my wife and I were doing some gardening yesterday and I suspect that it is likely just potting soil.

I also just put a test strip in the water... my free chlorine is reading a whopping 10. Guess I shouldn't have put a fresh chlorine puck in yesterday. Going to pull the puck out and put the pool back on circulate again while I go into work for a few hours today

I hate this pool. It is making a fool out of me.

Edit: I looked at the test strip again, it was reading free chlorine between 5 and 10, not 10, so it isn't as bad as I thought. In any case, I removed the puck. My pH was also low, so I added some more pH+

[Noggin]

I can actually see the 'stuff' floating in the water, it didn't seem to want to settle out like the pool store guy said it would so I set the filter to filter and let it run for a few hours until the pressure went up by about 3 PSI then I shut it down as I don't want it to run overnight right now.

Since I have 5ppm free chlorine and 0 combined chlorine, is it safe to assume that it isn't algae? Can algae even be white?

Maybe it'll be settled out by the morning.

How big are the flocc'ed particles when they settle to the pool bottom?

[Noggin]

The problem has not been solved, but please consider this topic closed. I now believe that algae is the problem and my CYA is too high. Doing a partial drain and refill this weekend, and replacing the sand. Going to shock the crap out of the pool until all life within 1/4 mile is dead. If it's algae, they will come to fear my pool.

Edit: For the future benefit of anyone that reads this... I don't know what initially caused the cloudiness, but the clarifier made it worse and the floc made it terrible. The floc didn't want to settle for even if I left the pump off for a long period of time until about 3 or 4 days after I initially put it in. I was able to vacuum it up after that, but it was still somewhat cloudy. I replaced the sand and had to backwash every 4 hours or so and now my pool is clear: Picture

Ultimately, I think my problems were caused by old sand, it was probably near 7 years old. I don't think it was channeled (I assume that channeling is obvious and I didn't see anything that looked odd) I just think it was old and not filtering well.