SERVO, thats what I plan on doing myself actually. The only way I would want to afford a 500g tank is by using skylights and such other 'energy saving' methods. Its not just the electricity, but the fixture and bulb costs as well. I figure its pretty much break even to start, but not having to buy a crate of bulbs every year is a big bonus. I plan on using some arrays of 80 watt T5s to suppliment the blue of the tank as well as 'off-peak' viewing, but the sun will be the major method of lighting the tank. I will oversize the skylight, and then block out more than half of the glass with blue and purple films to provide a more pleasing color... as well as the T5's. If I was unable to do skylights, I would most likely cap myself at say... 300 gallons. Thats just alot of electricity to suck up otherwise.
As for the 500g, I plan on using Tunze Stream pumps of course, and a sump that is as close to the same height as the tank as possible, and a return pump that only does 2000gph most likely. The skimmer, which I have already, will be under 100 watts... so all in all, Im trying to keep the total pump wattage at about 600 watts (Tunzes may be 55 watts a pop, but they alternate max output between 2 pumps, so its more like 80 watts constant per pair), or $525 per year at $.10/kwh. That sounds like alot, but just consider HOW MUCH MORE those who run tanks this size have to spend on lighting then. Also, the tank will be in its own room, so all the heat and humidity will not tax the main house's A/C unless I leave the doors open (in winter though, its a giant heatsink). Since even the most efficient halides are still only 25% efficient (75% of the electricity goes directly to heat), thats a good thousand or so watts of heat that the tank wont generate in summer to tax the A/C, as well as humidity. In winter, the water will absorb the radiant energy of the sun and release it at night into the room... just like a solarium/sunroom with a dark tile floor. So the tank will help pay for itself by contributing to the home's heating. If I can, I will bury a couple water storage containers in the back yard as well and run heat exchanger loops instead of a chiller. On a hot day, all I will need to run is a small pump to run cooled water from the underground storage tanks through titanium pipes in the sump. Likewise, if the pipes were run through the basement or underneath the flooring on the first floor, it could help keep the house warm in winter, or soak up some more of that cool from the concrete in the summer. There is a website out there about how a guy cooled his 500+watt computer system with a water cooling loop and about 30some feet of copper pipe set on top of his garage floor. Thats some good heat exchange!
Pumps are pumps though... a watt of energy is hard to get around... as efficient as you can get, if you still need 1hp of pump to move enough water, you will need 1hp+ of pump... no way around it. The best thing to do it to try to put the least amount of head pressure on the pumps as possible and use flow-biased pumps with large diameter plumbing (or prop pumps for flow). You also dont need to move large volumes through your overflow/sump... beyond a certain point of say... 2x the tank volume per hour, you arent doing much more than just recirculating, and recirculating should be left to low-pressure pumps that dont have to pump against head pressure. If you want to start saving more on pump electricity, then yeah... you are looking at a solar array system... which considering the way things are going for energy, are a very good investment to consider. My father made his own solar array for hot water heating... in the freezing cold of winter, the water from the solar heater gets up to 150 degrees F easily (120+ is what most people consider 'scalding')... and runs forever (as long as there is enough sun out, lol, then the inline heater comes back on). Being able to shut off your hot water heater for 90% of its use is a nice saver. But even PV solar cells are a smart choice. The time is coming when you may no longer fill up at a gas station, but instead recharge your car's batteries at home. Demand for electricity would go up then, and solar panels are getting cheaper and cheaper all the time. Heck, with a car alternator, some batteries, and a controller/inverter, you can hook it up to your own wind turbine and make your own wind-generator for cheap. Ive seen guys DIY 1kW vertical wind generators like this for a few hundred $$$.
Hmm.... I like that project ^^^. If there is enough wind where I move, Im thinking I should make my own wind turbine for what... $1000 at most, and run my pumps for free. A 15' tall vertical turbine in 10 mile winds should do that easily.
The problem with PV Solar Panels right now is that they only harvest maybe 10-15% of the light that hits them... mostly red spectrum. Until they figure out how to make PV's that are more efficient, they are still worth it, but not AS WORTH IT when the higher power density ones come out later and can make 3x the power or more in the same area. One way to capture 100% of the radiation from the sun (even UV and IR) is to focus the light into a small area, like those 'radar dish' collectors mentioned before. The advantage is that by focusing alot of radiation into a small area that can capture it (like pipes painted black) is that you can capture nearly ALL of the radiation from the light. This is just like the solar water heater my father built, but we are aiming for 200+ degrees because then we will run the steam through a turbine generator (a water pump in reverse, sorta). The water itself can regenerate (the steam gets collected/condensed and recycled) and you have a very efficient and effective solar system. The cool thing is that other than the mirrored reflectors/reflectors (which themselves arent that technical), the system is remarkably easy to make. Once again, the only important parts that you MUST buy usually are the power conversion electronics and controls (phase/frequency conversion, furling control, overload protection). And these arent that technical either.
