It took you a month to fully fill your plaster pool?
What precautions did you take to keep the exposed plaster from damage?
It's not for everyone. But it works for me. And, truth be told, it saves the earth's resources, but you won't like to know how I do that.
Suffice to say I'm likely nothing like anyone you've ever met in terms of "typical pool owner" things that people do.
Anyway, I've done this before (it's not my first drain & refill - where I learn how to do it better each and every time, e.g.,
I learned what a much better pump was, over here); but I was in the hospital with life threatening issues so the pool went unmaintained because if I don't do it, it doesn't get done. The good news is that this year it's going to take less time to refill as the water flow is better than it is in most years, perhaps likely due to the atmospheric rivers we experienced in the winter replenished the always flowing underground rivers beneath my 400-foot deep wells.
Still, it will take, oh, I don't know, at least a couple of weeks though as I never really cared about the volume since I titrate frequently, but I started to think about using my college calculus concepts where I roughly measured the pool based on the water flow and found it's probably about 38K to 40K gallons (not that it matters as I dose to the observed measurements).
Some day I'm going to
model my pool with a free open-source
Windows 3D program such as Blender is.
Since I'm a DIY kind of guy, that will likely be its own thread on how to draw your pool in FOSS 3D software (and yes, I'm aware of methods espoused here for calculating volume using chemical titration methods).
We all put our CYA granules in a sock (I use a fine-mesh "delicates" zippered laundry bag) and put the sock in the skimmer or hang it in front of a return (mine goes in the skimmer), while the pump is running.
While I'm well aware of that common method, given my pool is a "self cleaning pool", my skimmers are not filtered, so it's probably not a good idea for all that stuff to go directly into the cleaning-jets pump which is something like 10 feet below the level of the pool.
You will not like how I maintain my pool (which wastes the least amount of the earth's resources possible - but which almost nobody would do except me - as I am a fanatic about DIY even as I know most people who own pools waste resources left and right in terms of running the pool equipment - which is a tradeoff in terms of effort - which I'm extremely well aware of - since the moment I stopped maintaining the pool myself for the duration of my long life-threatening injuries - I had to empty it to start over).
(Plus, I had experimented with borates - so I had to empty the water anyway as I wanted to test the theories out.)
Others here will have to weigh in if the same can be done with calcium chloride (I don't use that).
My well water is high alkalinity and low calcium so it's always a struggle to balance the temperature-based saturation index as it takes a lot of iterations with muriatic acid and calcium chloride at any given temperature - which I'm quite familiar with the process of. However, pouring acid columns isn't my thing and the salt is highly exothermic when it dissolves, so I use the logarithmic dilute:dilute:dilute method that many others also use - which requires buckets.
Liquid chlorine and muriatic acid get poured directly into the pool, slowly, in front of a return (while the pump is running). Salt pellets go right into the pool and get brushed around until they dissolve (takes about 10 minutes).
That's all the chemicals I've ever put in my pool, so no premixing for me.
I've seen your pouring and measuring solution before and I admire how well built it is, especially given almost all store-bought pool equipment is cheap expensive plastic garbage. One by one, I'm striving to replace the store-bought solutions with solutions that can last a year in the sunlight as I have infinite sunlight and no shade (nor do I have a pool shed).
I do use an all-plastic bucket to carry chlorine and acid jugs across my deck, just in case they leak or drip. But your "buckets" would not be good for that, as you need a handle. Like this:
View attachment 598620
Agree that the Blitz gas can (of which I have about two dozen) doesn't have a carrying handle. I was throwing them all away (I'm so happy Blitz went out of business - they have no business selling that expensive garbage) - when I hit upon the idea to re-use.

I'm all about re-use recycling. I realize almost nobody who owns a pool re-uses and recycles - but I re-use re-purpose & recycle everything. And I throw away nothing. I am well aware most people can afford to waste the earth's non-renewable resources & pollute left and right but I prefer to not be one of those people.
A hint is if a person's pool is beautifully maintained with no work on their part, then they're wasting the earth's resources.
Or, as it can be, they spent ten times the cost to implement a completely renewable energy system (e.g., off-grid pools).
The other "gizmo" in the pic is my solution for slowly dispensing liquid chlorine and acid into my pool above a return. I lift the jug out of the bucket, over the water, and pour it into the measuring cup in the gizmo. Then the jug goes back into the bucket. The jug is never held above the deck, so if it drips, the drips fall into the water or get caught by the bucket, not the concrete or stone.
When I first saw that, I toyed with the idea of making my own - as it's a WONDERFUL idea which is a very admirable solution! Kudos to you for engineering skill and ingenuity.
Obviously, I'm all for fabricating things that make pool chemical dosing easier and safer, but a repurposed gas can with its handle on the side, and no pour spouts, seems to me to be "reinventing" something that already exists in a much better form (for not all that much money). Sorry, you didn't win me over, but I applaud your effort.
Agree on the lack of pour spouts. I have it at the edge of the deep end as I dissolve the CYA (which you all know takes forever) and the CaCl (which you all know is highly exothermic) and then I just tip it over into the pool. I also use Bed Bath & Beyond stainless steel kitchen strainers to filter out the particles when I pour dissolving granules from a conventional bucket into the pool.
What's ironic is that a three-dollar stainless steel kitchen strainer is far better quality than anything I've ever seen in a pool store at any price - given all the pool stores sell, as far as I can tell, is expensive plastic garbage.
I gave up on my plastic gas cans, because they allowed evaporation. They sucked as gas cans. So they just sit empty in my yard. I get wanting to recoup that investment, but I just wrote them off as the loss that they are.
Many years ago, when I first built my home gasoline refueling station, I contacted the CHP & OSHA & the local Fire Marshall and the County Zoning folks, etc., but the most productive conversations were with Mike McCarthy at CARB where I impressed upon him how horrid the California gas cans are (which the EPA adopted so that everyone in the USA gets the same garbage gas cans). The CARB (and then EPA) spec'd the gas to stay inside the can for six months in ambient temperatures (they have a shorter-time test bed where they weigh the gas evaporation) and every can sold has to meet that requirement to stay inside the gas can.
The problem as I explained it to Mike was simply that
they never spec'd the gas to come OUT of the can - which - as we all know - doesn't.
Worse, while some cans (such as the Spectre Jerry Jug) barely leave a few drops when you siphon or pour, others (such as the abominable Blitz) leave multiple tablespoons of the gasoline after siphoning or pouring - every single drop of which will go into the atmosphere - simply because the CARB (and later, the EPA) never bothered to test portable gasoline containers for "leftover" fuel at the bottom after a full upside-down pour.
It's almost criminal how much fuel ends up in the atmosphere between a Blitz & a Spectre!
All that pollution hurts me when I see it - as the whole point is to preserve the earth's precious non-renewable resources, after all.
Long ago I gave up on the pouring spouts in favor of siphoning as I refill four cars after going on a bi-weekly trip to Costco to get Top Tier (polyetheramines) gasoline at a good price. (Some day I will invest in a McMaster-Carr 12VDC gas pump in a epoxy-lined steel drum but for now, I meet all local state and federal regulations (even OSHA) with my siphon system where I drive a vehicle under the portable gas cans and fill up each vehicle, one by one, at home (just as I do all my mechanics work at home on 30-year old cars with over 300K miles - as I said - I prefer to not waste the earth's resources if I don't have to - but I do fully understand that most people "say" they care about the environment but they waste its non-renewable resources left and right).
PS. Again, I don't use calcium chloride, but I have direct experience with liquified CYA staining my pool finish. So not only will I never again use liquid CYA, I would never pour it into my pool. That's why I only use granules, and only in a laundry bag in the skimmer. And mixing CYA over your coping and deck, or setting down your various mixing utensils on either, is an excellent way to stain deck or coping or both.
I used liquid CYA only once as it's too expensive in favor of, for years, I used to go to the pool-supply houses at opening time (not to Leslies) where I could often find the hourly-paid stocking guy would sell me (often under the table as I have eyes that know all about the cash register receipt game) the CYA fine powder, but it was a pain to always have to ask the guy to go to the back room and weigh me out some - and truth be told - the powder has its own serious issues (e.g., solidifying in your lungs) so I finally gave up on both the CYA liquid and soft powder and went to the rock-hard CYA granules that most other people use.
Side note: Since I happen to have eyes, I can see if they ring it up at the cash register - which - I'm no vigilante - I don't care about; but - it's kind of ironic they sometimes charge me the sales tax that they're not paying (but most of the time they just rough it out) after they've scooped the powdered CYA out of big blue barrels from the back room storage area for the pool professionals into my Costco Psyllium containers (I happily re-use almost all Costco containers - especially the mixed-nut jars!).
This is why we all put our chemical into the pool or skimmer, and don't premix. The more you handle pool chemicals, the more likely it is you'll get into trouble. Either sloshing it onto your deck and causing permanent stains (I've done that), or worse, getting some splashed into your face/eyes (yep, done that, too).
Your advice is sound as I'm quite familiar with "intentional lab accidents" (we used to make our own explosives in the college inorganic, organic and biochemistry labs) as there are inherent dangers when mixing acid:base mixing, redox potentials, and exothermic reactions, all of which are naturally inherent in pool chemistry. (In the physics labs, we used to blow up the ~30VDC electrolytic capacitors in the 120VAC sockets as a different set of "intentional lab accidents", as young invincible college boys always love to experience explosive action at a distance!).
It's just not best practice, at all. (Excuse the tough love, but I had to learn all this the hard way, more than once!)
Don't worry about the tough love as I'm an aspy who does things for the pure joy of saving the earth's resources and in the ecstatic feeling of doing what we're always told by people who never did it that we shouldn't try to DIY (e.g., my mom told me not to run with scissors and now I run with chainsaws!).
To be clear, we were all likely told to pay a professional to do everything around the house, and yet, those who DIY climb on our roofs with ladders (which our mother also told us not to do) and we all chain saw trees (again, which we're told not to do ourselves) and we also mount and balance our own tires at home (which we're told is too dangerous to do), etc., so it's not surprising that we're also sometimes told not to mix our own pool chemicals in a bucket but to let the automated systems do it for us.

Personally, if someone who has a pool tells me he has no buckets, I'd look at him kind of funny - just as I would someone who owns a car but doesn't have ramps/chocks/stands/floorjack/transmission-jack/etc. - as that either means he doesn't do anything himself or that he has an automated system that does everything for him - much like I'd look at any person who has never mounted and balanced a tire at home (they pay other people to do what they could easily do themselves - and that's ok - as it's a philosophy to do things yourself, DIY, that most people pay other people to do for them).