OP
OP
chipmunkofdoom2
Always Making Something
Thanks @saltyfilmfolks 
no worries, a lot of the post isn't really required reading, it's more for background knowledge. I've been thinking about writing up a few shorter articles more like "how-tos" on specific topics, like putting together a cheap and simple battery backup for Ecotech Vortech pumps or Jebao Wavemakers, but I just haven't had the time.
You're definitely right, a strictly-DC system is going to be much more efficient than using an inverter. Inverters get up to 90% efficiency, but often that efficiency is much lower unless you approach 100% of the inverter's rated capacity. Heaters aren't usually required in emergencies anyway, and even in colder climates, I wouldn't try to run one on an inverter. They suck up way too much power. The tricky part is DC-only systems are a bit more complex because the DC pump options on the market vary so much.
If you have Ecotech Vortech pumps, the system can be really straight forward. All you need is a 12V battery, a charger, battery clamps to connect to the battery (optional, depending on the battery terminal type), a 1.3mm x 3.5mm plug (I think it's 1.3mm x 3.5mm, check before buying) to plug into the Vortech controller, and some spare wire. To set up the system, first you solder some wire to the plug (I think center pin is positive, again, double check). Next, attach the other end of the wires to the battery (via the clamps or by screw terminals). Plug the plug into the Vortech's battery backup port. Then, attach the battery charger to the point of sale/neg terminals on the battery. Finally, plug in the charger. When the power fails, the battery will power the pump through the backup port. When the power comes back on, the main power supply will power the pump again and the charger will recharge the battery so it's ready for next time. That's an Ecotech Vortech battery backup for about $80 - $90. Fun fact, the Ecotech battery backup actually contains a 35Ah battery, so this system will give you the exact same run-time as an Ecotech battery backup for half the price (pretty sure it'll void your warranty though, so do this at your own peril).
For Vortechs, it's easy because the backup port does the automatic switching for you. The Vortechs will also take 12VDC directly and don't require any step-up or step-down of the DC voltage. For most other DC pumps, it gets a little more tricky.
Take Jebaos for an example. I've read that the Jebao Wavemakers will take a 12V power source, but they'll only run at half speed (not really a problem in a power outage as it will conserve power). The problem is they don't have an automatic switch. You can basically handle this in one of two ways. You can build a system like the one above and add a 24VDC relay. The relay can be powered by the Jebao power supply. When the power is on, the relay is energized and the Jebao power supply powers the controller. When the power fails, the relay closes, and battery power runs the controller. When the power comes back on, the Jebao power supply begins powering the pump again, and the battery charger recharges the battery. Not terribly complex, but you have to know about relays and how to set them up.
Another option for the Jebaos is to use a "direct" approach and power the pump directly from a 24V battery system. Basically, you would use two batteries to create about 24VDC and always run the pumps off that. You would attach a 24V power supply instead of a smart charger. When the power is on, the pumps draw from the power supply. When the power is off, the pumps draw from the batteries. When the power comes back on, the power supply charges the batteries and powers the pumps. So, in this case, you buy two batteries and wire them in series. You buy a 24VDC power supply and attach it to the circuit to keep the batteries charged. You attach the batteries to your pump and you're done. This approach is simpler, but it's not ideal for several reasons.
First, 12V batteries can be held a continuous voltage, usually 13.6V - 13.8V (this is called floating). While batteries have pretty good life expectancy when stored at float voltage, the problem is they are never fully charge after discharging. A full charge for a lead acid battery usually involves going above 14V for a brief period. If you float a battery at 13.6V, it'll never actually get to the 14V range, which could lead to sulfation or stratification. This could reduce the life of the battery. The smart chargers I recommend usually involve a cycle at 14.2V - 14.6V, so they avoid this concern. I don't have any good data to back this up, but I believe having proper charge cycles keeps the batteries better for longer.
The second problem is the float voltage. A 24V battery bank will actually have a safe float voltage closer to 27.2V - 27.6V. It's easy to find power supplies that provide 24V. It's much more difficult to find power supplies that supply between 27.2V - 27.6V. Not impossible, just difficult and expensive. A related problem is that most pumps (the Jebao included) are likely set up to take 24VDC, not 27V - 28V. If you attempted to run a 24V system on almost 28V, I'm not sure how it would behave long term. Those extra 4V might not be a problem, but the might be.
A third option for Jebaos is to run a "direct" system with a 12V battery bank (and 12V power supply), but run the power through a 24V step-up converter. This would work like the 24V system, except it's cheaper because you only need one battery and the pump will always get 24V because of the converter. The downside with this, again, is that you're floating the battery (might reduce life expectancy) and it's hard to find 13.6V power supplies that give a proper float voltage.
Another anciallry concern with both the 24V and 12V "direct" systems have more points of failure. In both systems, your pumps, whether the power is on or off, rely on a commodity 12V or 24V power supply (the one that charges the batteries and runs the pumps). In the 12V system, you have an additional point of failure, the 12V to 24V converter.
Ecotech Vectras and Jebao return pumps are a different can of worms. I'm not sure Jebao returns can run on 12VDC, and Vectras (I believe) run on 36V. So the answer gets even more complicated if those are thrown into the mix.
So I don't know if I answered your question, or just gave you more questions to ask but either way, let me know if you have any other thoughts and I'd be glad to help out if I can
no worries, a lot of the post isn't really required reading, it's more for background knowledge. I've been thinking about writing up a few shorter articles more like "how-tos" on specific topics, like putting together a cheap and simple battery backup for Ecotech Vortech pumps or Jebao Wavemakers, but I just haven't had the time.You're definitely right, a strictly-DC system is going to be much more efficient than using an inverter. Inverters get up to 90% efficiency, but often that efficiency is much lower unless you approach 100% of the inverter's rated capacity. Heaters aren't usually required in emergencies anyway, and even in colder climates, I wouldn't try to run one on an inverter. They suck up way too much power. The tricky part is DC-only systems are a bit more complex because the DC pump options on the market vary so much.
If you have Ecotech Vortech pumps, the system can be really straight forward. All you need is a 12V battery, a charger, battery clamps to connect to the battery (optional, depending on the battery terminal type), a 1.3mm x 3.5mm plug (I think it's 1.3mm x 3.5mm, check before buying) to plug into the Vortech controller, and some spare wire. To set up the system, first you solder some wire to the plug (I think center pin is positive, again, double check). Next, attach the other end of the wires to the battery (via the clamps or by screw terminals). Plug the plug into the Vortech's battery backup port. Then, attach the battery charger to the point of sale/neg terminals on the battery. Finally, plug in the charger. When the power fails, the battery will power the pump through the backup port. When the power comes back on, the main power supply will power the pump again and the charger will recharge the battery so it's ready for next time. That's an Ecotech Vortech battery backup for about $80 - $90. Fun fact, the Ecotech battery backup actually contains a 35Ah battery, so this system will give you the exact same run-time as an Ecotech battery backup for half the price (pretty sure it'll void your warranty though, so do this at your own peril).
For Vortechs, it's easy because the backup port does the automatic switching for you. The Vortechs will also take 12VDC directly and don't require any step-up or step-down of the DC voltage. For most other DC pumps, it gets a little more tricky.
Take Jebaos for an example. I've read that the Jebao Wavemakers will take a 12V power source, but they'll only run at half speed (not really a problem in a power outage as it will conserve power). The problem is they don't have an automatic switch. You can basically handle this in one of two ways. You can build a system like the one above and add a 24VDC relay. The relay can be powered by the Jebao power supply. When the power is on, the relay is energized and the Jebao power supply powers the controller. When the power fails, the relay closes, and battery power runs the controller. When the power comes back on, the Jebao power supply begins powering the pump again, and the battery charger recharges the battery. Not terribly complex, but you have to know about relays and how to set them up.
Another option for the Jebaos is to use a "direct" approach and power the pump directly from a 24V battery system. Basically, you would use two batteries to create about 24VDC and always run the pumps off that. You would attach a 24V power supply instead of a smart charger. When the power is on, the pumps draw from the power supply. When the power is off, the pumps draw from the batteries. When the power comes back on, the power supply charges the batteries and powers the pumps. So, in this case, you buy two batteries and wire them in series. You buy a 24VDC power supply and attach it to the circuit to keep the batteries charged. You attach the batteries to your pump and you're done. This approach is simpler, but it's not ideal for several reasons.
First, 12V batteries can be held a continuous voltage, usually 13.6V - 13.8V (this is called floating). While batteries have pretty good life expectancy when stored at float voltage, the problem is they are never fully charge after discharging. A full charge for a lead acid battery usually involves going above 14V for a brief period. If you float a battery at 13.6V, it'll never actually get to the 14V range, which could lead to sulfation or stratification. This could reduce the life of the battery. The smart chargers I recommend usually involve a cycle at 14.2V - 14.6V, so they avoid this concern. I don't have any good data to back this up, but I believe having proper charge cycles keeps the batteries better for longer.
The second problem is the float voltage. A 24V battery bank will actually have a safe float voltage closer to 27.2V - 27.6V. It's easy to find power supplies that provide 24V. It's much more difficult to find power supplies that supply between 27.2V - 27.6V. Not impossible, just difficult and expensive. A related problem is that most pumps (the Jebao included) are likely set up to take 24VDC, not 27V - 28V. If you attempted to run a 24V system on almost 28V, I'm not sure how it would behave long term. Those extra 4V might not be a problem, but the might be.
A third option for Jebaos is to run a "direct" system with a 12V battery bank (and 12V power supply), but run the power through a 24V step-up converter. This would work like the 24V system, except it's cheaper because you only need one battery and the pump will always get 24V because of the converter. The downside with this, again, is that you're floating the battery (might reduce life expectancy) and it's hard to find 13.6V power supplies that give a proper float voltage.
Another anciallry concern with both the 24V and 12V "direct" systems have more points of failure. In both systems, your pumps, whether the power is on or off, rely on a commodity 12V or 24V power supply (the one that charges the batteries and runs the pumps). In the 12V system, you have an additional point of failure, the 12V to 24V converter.
Ecotech Vectras and Jebao return pumps are a different can of worms. I'm not sure Jebao returns can run on 12VDC, and Vectras (I believe) run on 36V. So the answer gets even more complicated if those are thrown into the mix.
So I don't know if I answered your question, or just gave you more questions to ask
but either way, let me know if you have any other thoughts and I'd be glad to help out if I can 
