I punched a hole in my gunite pool, broke down the sides, filled in half. If I had it to do over I'd go down the path you are Buster. I'd double check the thinking on needing to provide pressure against the sides so the pool does not crack. I know other types of pools require this, but I don't see why gunite would. This was the strongest concrete I have ever removed. I'd also double check the code for depth. The deepest I had ever heard was 24", a few places it is 18". No worries about chlorine as you said. It doesn't leach into concrete in any amount worth considering. My bottom drain became cogged pretty fast. The pool pipes really aren't large enough for the amount of muck a pond produces. I think you may be over thinking the metal culvert deal if I understand correctly. Just running 3" ABS pipe from the bottom up and out against the side would be enough. You could put a few of these in if you wanted, or a few 1.5". The fabric I think wouldn't work very well. I've used drain fabric a lot and it has a lot of great uses in ponding, but it clogs really fast unlike in ground use. If you fill with stone you'd have the mother of all filters. You can pull water off the bottom or push it up, or switch from time to time. Bio really isn't an issue with a small fish load, just the sides and bottom of the pond would be more than enough to cover that. But large stone filters have other benefits for water clarity. Sure, at some point it does fill with silt but that could be 5,10,20 years and there are lots of things you could do to reduce that. With stone I wouldn't worry much about using perforated pipe. You'll get way enough flow without it, but it can't hurt either. If you really wanted some I'd use the 3" perforated flex drain hose Home Depot has in 100' rolls. Cheap, plastic and built to stand up buried. That amount of stone isn't cheap. I got free dirt and put a liner over that. Companies are happy to deliever all the free dirt you want, no delivery charge. Just an option. I'd go with the stone if money wasn't an issue. The shape of rocks in the bottom looks great, but color disappears very fast as they are covered with silt, algae or bacteria film. So I wouldn't worry about the rock color. I would mortar the top layer of rocks together just to make cleaning easier. If you use the stone as a filter you can just leave some openings. You are dead on with your ideas for sand bags and plants around the edge. No one will ever think it was a swimming pool. However, I wouldn't use sand bags, at least the white plastic mesh type. They break down really fast, like a year or less depending on sunlight. And the mess that makes is a real big pain. Cloth with break down too. I'd go with stacked rock or fake rock from concrete or concrete block. This will be way cool. This type of set up allows for so many options and changes can be made later. I'm jealous.

Being in Texas, saving water is an important aspect. Cartridge filters help some in that they don't get backwashed. Have the PB put a 3 way valve on the pump exhaust so you can lower the water or vacuum to waste with a cartridge filter. Some PBs put a hose spigot on instead but this prevents vacuuming to waste. Your fill water is pretty hard but not overly so. Calcium will build up in the water so watching it is called for. It is one of the chemicals in pool water that can only be removed by diluting. The water has a slightly high pH and high alkalinity. This will need to be brought down with acid added. Not a big deal to do but skipping it will cause the calcium to drop out of solution and stick to various surfaces like steps and pool walls and floors where the circulation is slower. This is called scaling and is random in where it occurs in the pool. It also takes time to form and is a gradual process. It isn't something that would stop you, just something to be aware of when maintaining your pool. While seemingly premature in the discovery process of building, taking it into account can help you later in making your equipment choices and layout. Blazing hot means a relatively a high evaporation rate. Have an auto-filler so you don't have to put a hose in every day during the Summer. Remember, calcium doesn't evaporate so the CH value will rise. Occasionally, you will need to lower the water in the pool and put in a significant amount of fill water. This will also lower your salt level and raise your alkalinity and pH levels when you refill. Your blazing hot Summers may lead you to a desire for a cooling solution. Some opt for a heat pump that works in reverse or solar panels that when the pump is run at night, radiate the heat and cool the pool. Please note that this is additional run time. A pool pump needs to run during the day. Scott

Ethiojazz your main factor when it comes to tile/coping this time of the year is going to be freezing temps. If the mortar is wet and it freezes overnight, the water in the mix will freeze, creating many little voids in the mortar - which can potentially lead to problems down the road. But - there are a couple "tricks of the trade" that can be applied here to prevent this from happening. In addition, temps in the area are kind of jumping around (i.e. one night it's freezing, next night it isn't). So there is still time ... On the other hand, the only real "damage" done if you wait is just in scheduling. If you're having a deck done, 99% of the time you'll need the tile/coping installed first. So this would hold up decking progress. If you're doing a regular concrete deck ... obviously this would not be much of a hold up. Now, if you're doing flagstone, or pavers ... yeah, you'll lose some time.

OP states-"I am installing a new ABOVE GROUND pool" Most of the ABOVE GROUND pools (depending on size) use self contained, fully insulated filters that run on 120VAC with a standard plug in type cord. There are not heaters, pumps, etc that are used and would require bonding, etc. Lets make sure we are all talking about the same thing-this is different than an in-ground pool. It may be that the (15A/20A) 120VAC outlet is what was used for the previous ABOVE ground pool. I agree that new would probably be better. Admittedly, there is still the potential for shock and electrocution, but let's find out what is being proposed first!