Does using a heater with higher watts than needed use more electricity? My guess is not as although it's using more power while running it should get to temp faster so it's on for less time. Does this make sense? I want to go with a higher wattage just in case the room gets colder.

Yes, a higher wattage heater uses more power while it's on, but not more power over time, unless the heater is struggling to keep up, in which case the lower wattage heater will cap at its maximum usage.

I like having higher total wattages than I think I need just in case, but it's more important to me to have redundancy, because I've had a lot of failed heaters over the years. I usually have more than one heater in a body of water, totalling a bit more than I think I need, with spare heaters (and pumps) on hand if needed.

Good points, especially about redundancy. One issue i had with a standard aquarium heater is it would shut off sometimes before reaching set temperature. I was using 3 300-watt heaters. Replaced one with a hygger 500 watt and it's working better. I'm thinking of getting another Hygger but 800 watts to replace the remaining 2 300-watt heaters. The hygger seems like a much better unit than the Aquatop/Marineland heaters. Almost industrial like. Pond is 125 gallon and ambient temp is around low 60's at night. This summer i'll try to figure out a way to better insulate my single pane glass Greenhouse.

A watt is a watt is a watt. Doesn't matter if it is less wattage or higher wattage, a watt can only produce so much heat. We are billed by watts. Now, the amount of wattage will depend on the upper temperature you want to keep the pond. Lower wattage will take much longer than higher wattage to get it up to desired temperature, and lower wattage may not do it depending on the volume of water and how many watts the heater is putting out. More wattage will get the temp up faster. But as far as heating the water, a watt is a watt is a watt. There is no way to "cheat" the electric meter to get to a desired temperature.

As I noted elsewhere, I'm currently running Hygger 500 and 800 watt models on one of my pond systems. They've been good so far, but one of them has a poorly adjusted thermostat, so is consistently reporting 5 degrees off.

I find that it is very common to have accuracy issues on aquarium heaters, but usually they have a consistent offset, so you can take that into account once you compare their behavior with a known good sensor. Likewise, I often put new heaters on a kill-a-watt device to determine their actual power draw. Usually they draw a little under the rated amount, but sometimes they are a lot lower than rated.

You would think with digital tech they would be more accurate. Hygger says it uses a dual temp probe for better accuracy. Guess that may be just advertising bs.

You would think so. I think the issue is they don't bother to calibrate, so they're all over the place. These pictures were taken at the same time, showing the displays on the two heaters and on the temperature probe in the water. The moral of the story is don't trust the temperatures that cheap electronics report, and if possible, do an offset calibration of your own so that you can set the thermostats accordingly.


I have a power cut off probe on these for runaway heating events, and the remote probe has been calibrated independently to within 1 degree F. I can't complain about the Hyggers when I have yet to receive an inexpensive heater with an accurate thermostat, and some of them in the past have been 10 degrees off. It does make me wonder if I should check to see if there's a calibration function available on either of these, though.

Am i reading your pics right? 73, 77, 67? That's a big difference. I'm ordering a Hygger 800 to go with my 500 so i can ditch the 2 300w heaters that are hard to tell if on [lights don't show well in the pond]. A total of 1300w should be enough to heat my 130-gallon pond to the mid 70's. Edit to add are all the probes in the same area? Water may be warmer next to the heaters.

77 is the set temperature. The heaters are reading current water temperature of 73 and 64.5. The calibrated monitor probe is about a foot closer to the waterfall return (never downstream of the heaters) and reads 67.3, so between the other two. You're right that the heaters could be affected by their own heat, but there's no accounting for the reading of 64.5.

Yes it's confusing, being sealed units to make them waterproof there's probably no easy way to calibrate them. You set the pond to 77 degrees? Most non tropicals like koi and goldfish can take it much cooler.

I don't heat the koi water unless I've got fry in the winter, in which case they prefer it much warmer like this. These measurements are taken from the tilapia tank.

Tilapia? There from South America right? Guess that's why they need it warm. Do you raise them to eat of sell commercially? I would guess you need a pretty big pond.

Tilapia grow very quickly, when warm enough and fed often enough. They're much more efficient than carp, so need less water per fish. I have blue tilapia, from the Americas, and Nile tilapia, from the other side of the world. I raise them just for myself. There are a lot of regulations that need to be met to do it commercially, especially here in Washington where aquaculture is so heavily controlled.

You can have a catch it yourself fish fry. I ordered the 800-watt Hygger, i'm tired of monkeying around trying to get a proper temp with the standard heaters. I really like the 500w so adding the 800w, seems like the best way to go.

Just to update i added the Hygger 800 watt to the Hygger 500 watt in my GH 130-gallon pond. Set the temp to 75 degrees and both units reading 74.4 today. With the multiple 300-watt heaters i could not get the temps right, i'm very happy with this set up. Might have to up them a few degrees when i add Discus but i'm sure they can handle it.