I store my hardy waterlilies in the tubs they are growing in, still wet, in closed garbage bags in the basement. Cut off all of the lily pads and flower stems, and let them go dormant for the winter. There is not enough sunlight or warmth to allow them to grow and flower in the winter anyway. I open the bag once a month, if I remember it, just to exchange the air. In the spring they are starting to re-sprout new leaves, and they are ready to be divided and re-potted, fertilized, or just put directly back into the pond. They could stay out in the pond as long as they don't freeze but my pond is only 2 1/2' deep so I don't risk loosing them, and just haul them into the basement. I've wintered them over for 15 or more years this way.

I hate to say this but this happened to us last year and the issue was answered extensively. The subject was "Grossed out & Disgusted" and this is the link - http://ths.gardenweb.com/forums/load/pools/msg071419062694.html I went overboard and shocked the pool, keeping the free CL at 12 for 72 hours. I then backwashed the DE filter shocked it again to achieve free CL of 12. I waited until the CL dropped to 4, backwashed again, and finally opened the pool. This happened to us in early August and was not how we had planned on spending the hottest part of summer. Good Luck and PS, I had managed to forget this incident until you reminded me.

Well, I can give you a ballpark estimate for the maximum (upper bound) possible difference in temperature of the water between a white surface pool and a black surface pool, but I probably can't give you even a ballpark estimate for the absolute temperature of the pool, that would require too many details of energy balance and energy transport. Let's say that for 4 hours, the sun is roughly directly overhead the pool, so that the black surface at the bottom of the pool basically absorbs ~100% of the sunlight it receives (black asphalt for example would absorb about 90%, so we aren't making a big error here). Assume then that a white surface will reflect ~100% of the energy (a very white substance like snow would reflect ~90% so we aren't making a big error here either). The flux of energy coming from the Sun is ~1400W/m^2, of which ~70% reaches the ground (the other 30% gets reflected by the atmosphere or clouds). Multiplying this by the surface area of your pool: 1400W/m^2*70%*(6m*4m+2*1.5m*4m+2*1.5m*6m)~53,000W of power that could be absorbed by your pool's surfaces. This is definitely an overestimate. Now over 4 hours, that 53,000W corresponds to 220kWh of energy. If all of this energy was deposited into the water (assuming the pool is well insulated from the ground), then this energy would go into heating the water. How much heating is that? Well, the specific heat of water is ~4000J/kg/degree C, so we need to know how much water is in our pool. The density of water is 1000kg/m^3. Multiplying this by the volume of the pool, we have: 1000kg/m^3*(6m*4m*1.5m)~36000kg. Now finally, we find that the temperature difference between a black pool and a white pool is: Δ T m a x = 220 k W h 4000 J k g ∘ C ∗ 36000 k g ≈ 5.5 ∘ C ΔTmax=220kWh4000Jkg∘C∗36000kg≈5.5∘C So, roughly 5.5 degrees of difference at most, which is not bad if you ask me. Reference https://www.physicsforums.com/threads/using-dark-tiles-to-heat-a-pool-via-absorption-of-solar-energy.747600/

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