Mixed Chemicals = Cloudy Swim Spa / Pool

[PoolDoc]

When I initially had the pool installed we tried to use plain bleach to chlorinate, but it seemed like no matter how much we added (in some cases multiple gallons), it was never enough and the pool eventually had some sort of algae or bacteria floating in it.

. . . . .

Also, draining and refilling every six months isn't an option, unfortunately, as heating 3000 gallons to 95 degrees using the stupid electric heater can take 5-7 days of 24/7 use, resulting in electric bills over $1k for that month.

Chlor-Brite is dichlor . . . if you've been using that for 2 years, wow! Your stabilizer level must be really high. You NEED that Taylor testkit.

But chlorine is chlorine -- if you aren't losing to sunlight, then when you lost the bleach, you would have lost an equivalent amount of Chlor-Brite. There may have been 'goo' in your unit that you cleaned up with bleach before you switched to dichlor. Or, you may have been buying "pool bleach" which can often (especially in summer) have less, possibly much less, chlorine than the label says.

Regarding refilling, if you can't do it 2x a year, at least do it annually. You can refill now, and the incoming water (at least here in Georgia is around) 75 degrees.

But lemme do some calcs:

3000 gal * 8.3 #/gal = ~25,000 lbs of water.
delta T = 95 - 70 = 20 degrees (now)
delta T = 95 - 35 = 60 degrees (winter)
BTUH req'd = 25,000 * 20 or 500,000 BTUH (now)
BTUH req'd = 25,000 * 60 or 1,500,000 BTUH (winter)
3412 BTUH = 1 KWH
So you need . . .
500,000 / 3412 KWH in summer = 146 KWH
1,500,000 / 3412 KWH in summer = 439 KWH

The highest residential rates I know of are less than $0.20/KWH, so summer water heating costs should be $29 and winter should be $87.

Let's keep going. A standard inconel sheathed 4500W water heater element requires a 30A 220V circuit, costs about $30 and can be set in 2" copper pipe, if you maintain continuous flow. It transfers heat at over 98% efficiency and is compatible with pool water. It should heat your pool in summer in 33 hours, and in winter and about 100 hours in winter.
[ 5500W: http://www.amazon.com/Camco-02933-Sc.../dp/B001RD7MK0 ]

So . . . if it's costing you anything approaching $1,000 to heat a fresh filled spa, something is seriously wrong, either with your installation, or my calculations.

[chem geek]

The highest residential rates I know of are less than $0.20/KWH, so summer water heating costs should be $29 and winter should be $87.

Just FYI, my marginal electricity rate in northern California is 40 cents per kilowatt-hour where I am in the 30-40 kWh/day range in usage. This doesn't change the conclusion of your analysis however. It should not cost anywhere near $1000 to heat the spa. It also probably does not need water replacement any more frequently than every 2 years, maybe a little longer if properly managed (unless the bather-load is higher than one person for one hour or so each day).

Also, it's BTU, not BTUH. BTU is an amount of energy so in the same units as kWh. Kilowatts is power (rate of energy per time) while kilowatt-hours is energy.