Thank you *so* much. Seems like you totally "get" where I'm coming from, and how I'm concerned about the potential future butt-kicking this is going to give me.

The location is Round Rock, just north of Austin.

I get Sun/Mon off, so I'll go back on Tues and do as you suggest in the evening. However... I've been rummaging in the shed, and have found out a fair bit of stuff that *might* help

Water Reports:
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In the shed I found some water reports! Now, I'm sure the readings and recommendations are way out of date, so I've ignored those completely, other than to note that there was probably a reasonable amount of stabiliser put in there at some point. That's going to have been eaten by the algae, so that's going to likely need a ton of chlorine to clear out.

There's a "Self Chem Solutions pool water analysis report" with some useful info.
Water volume - 15000 gallons
Attached Spa - Y
Filter Type - S (sand?)
Finish is "C" - concrete? That's what my boss said it was.

There's also a "Leslie's Water Analysis Report", in which some values differ.
Water volume - 15000 gallons
Type - Pool&Spa
Sanitizer - Chlorine
Surface - Plaster/Marcite - what's the difference between that and concrete? Are they the same? If not, how do I tell who's right?

Then I went out to look at the confusing and scary mess o' pipes.


Hardware:
---------
I don't know what any of these do, nor how to use these, and would appreciate advice, especially with the valves.

There are three "Jandy Valve Actuators" with wires going off. These have levers that were used to control the flow, back in the day. I think before even that, there was some kind of remote, timed computer control of these: there's a control panel in the kitchen but I'm told it doesn't work any more.

Valve 1 - Model UVA2440. Back pipe goes to pump, left to sand filter, right (via energy filter) into the ground.
Valve 2 - Model GVA-24. Back pipe goes to pump. Left and right go straight into the ground.
Valve 3 - Model UVA2440. Back pipe goes to water heater via Chlorine Feeder. Left and right go straight into the ground.

There's a big round "Hayward Pro Series High Rate Sand Filter". Three pipes lead from this. One seems to be for draining: it just leads to the lawn. One goes to the heater, and one goes to valve 1

There's a big box with the logo "Rheem" on the front, and a control panel. From all the warnings on it, I'm guessing this is the pool heater. Model is P-M267A-EN-C. Two pipes lead from this, one to the sand filter, one to the chlorine feeder.

Between heater and valve 3 is a Pentair "Model 320 Automatic Chlorine/Bromine ....ine Feeder" (label has degraded, some letters illegible).

There's what I guess is the pump, labelled "Emerson 1081 Pool Motor", between valves 1 and 2. It's marked as "230v, 60hz, 2.0hp, 10.5 sf amps" - I don't know if that voltage means it has a special power supply, or if that's its max rated. Anyway, a 2HP pump is going to cost about $100/month just to have running, I think. I need to run the numbers on that. But it's not looking good

There's a "Jandy Energy Filter" connected between valve 1 and where the pipe disappears into the ground.

A "Polaris" residential swimming pool and spa air blower is on a pipe that rises from the ground.


Chemical Inventory:
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Purposes are just my best guesses.

For raising Chlorine/Sanitizing:
The pucks, I guess, are for sticking in the chlorine feeder, for chlorinating the pool once stabilised. Probably not useful for shocking?
- Solutions "3in Super Pucks chlorinating tablets" - 4 x 7oz pucks
- Leslie's "3in Jumbo Tabs", stabilized chlorinating tablets 99% trichloro-s-triazinetrione (available chlorine 90%) - 9 pucks.

For raising Calcium:
- Solutions "Equalizer 300" Calcium Chloride 100% - 3lb
- Ram "Hardness Control" Calcium Chloride - 3lb

For raising pH:
- Leslie's "Alkalinity Up" Sodium bicarbonate - 10lb
- Solutions "Equalizer Plus 200" Sodium Carbonate 100% - 1lb
- Solutions "Equalizer 100" Sodium Hydrogen Carbonate - 4 x Half an 18-lb bucket
- Regal "pH Plus" Sodium Carbonate 100% - 1lb
[If alkalinity is high, avoid Sodium carbonate, use borax instead]

For lowering pH:
- HTH congealed "pH Minus" Sodium bisulfate 92% - 3.5lb
- TransChem "Muriatic Acid" 20deg Baume Hydrochloric Acid 31.45% - 2 x 1 gal

For Algae:
- HTH "Super Algae Eliminate 60" 60% Poly {oxyethylene{dimethylimino}ethylene, {dimethylimino}ethylene dichloride } (That's PolyQuat, right? A quart of this chucked in the pool sounds like it should help, but is it OK to put in at the same time as the bleach?)

Cleaning Stuff:
- Solutions "Suspend M+S" metal and scale control "contains phosphoric and other inorganic acids" - 1.5Qt
- Solutions "Filtex-G" Filter Cleaner and Degreaser - 0.5Qt
- Aqua EZ Cartridge and DE Filter Cleaner - 6 fl
- Solutions 1qt "Strip-off" surface cleaner contains hydrochloric acid, phosphoric acid and detergents

Also misc non-pool-related stuff, probably: Miracle Gro, Windex, Unlabelled purple bottle, unlabelled blue bottle, engine oil, WD-40, roundup, green light pest control.

I'd love to know which of these do what, and if there are any I should throw away, and how to correctly dispose of them if so.

I'm noticing a distinct lack of anything like bleach or chlorine. Should I chuck the pucks in, or bite the bullet and buy some DollarTree bleach?

How much will I need? Hrm. Assuming it's 6%, if I want 6PPM, I'm gonna need...
1PPM in 15,000gal = 0.015 gal = 0.06 quarts.
So 1 quart of 6% (0.06) bleach = 1PPM chlorine!
That makes my life mathematically easy, if I got the math right.

So to put in 5PPM, I'll need at least 5 quarts, so chucking in a couple of 3 quart bottles might do, though the algae might just use that up in a jiffy. I get the feeling from my reading that Chlorine's one of the things that's hard to seriously overdose with, especially in Texas' sun, and doubly so if this algae has been eating a lot of stabilizer.

Still, two bottles of bleach and one of polyquat in on Tues evening, and see how it looks when I get in on Wednesday.