View Full Version : What Size Heater
03-21-2010, 03:25 PM
What watt heater do I need for a 125 gallon? When I bought the aquarium, customer service said that two 200 watts would do the job. I don't think they are doing a good job. The heaters seem to be constantly trying to keep the temperature where it is set at. I have to mention also that the lid for the aquarium is still on order (they screwed up when this was all ordered and "misplaced" the lid). So could this be due to not having a lid on to help keep the heat in? The aquarium is still cycling so no fish in it.
This is the heaters I am using (two-200watt)
03-21-2010, 04:46 PM
The link doesnt work, but for most people that isnt adequate heating for a tank that size. Generally it is suggested you use between 3-5WPG on your tank to maintain it at temperature. If your house is more than 5 degrees colder than the tank, Id go for the higher end of that spectrum for sure. Simply adding a 3rd 200watt heater would probably be your best option, having multiple units means the tank will be more evenly heated. The lack of a lid on the tank can be contributing to the heaters having a harder time keeping the tank at temperature, but honestly the biggest problem is your heaters just dont have enough wattage to support the tank efficiently in most homes. :22:
03-21-2010, 05:06 PM
Thanks for the reply. I think when I pick up the lid next week that I will just grab another 200watt. It is a long aquarium (6 feet) and I can see where having three would probably work much better than two for even heating.
Don't know what is up with that link, worked when I posted it.
This is the heaters: Fluval E200
03-21-2010, 05:12 PM
Looks like a good heater and those 2 improvements will definatly help your heating cause :22:
03-21-2010, 06:22 PM
I personally use a pair of 250's in my tank and it keeps it spot on 76. I also place them right next to the filter intakes at either end of the tank and I'm using Jager heaters.
03-22-2010, 05:54 AM
I think I have the same size tank, 125g, 6 foot front. It has a 3 compartment hinged lid system, with the plastic cut-out strip along the back edge. Everything is tight fitting. I only cut two small notches, just large enough for the canister filters' hoses.
I have (2) each, Hydor Theo 300 watt heaters,
but one is adequate to heat and hold the water at 82°F if desired. I usually maintain it at 77°F, with the second heater set at 76°F, in case the first one fails. Each heater is placed vertically, next to each of the canister filters' intake tube; near or in the water flow.
We keep our house on the cool side in the winter. We have a setback thermostat and at night it goes down to 66°F, daytime 67-69°F, and in the evening we turn on the gas fire place, but rarely does the house get over 70°F unless we are doing a lot of cooking or baking.
I have had good reliable service with those heaters, but there is a recall on some of them:
I think you will find a tight fitting tank lid will help a lot. If you are buying another heater, consider a larger one; maybe a 300 or 400 watt; it would not cost much more, and probably require less "on-time". It does not hurt to have a spare heater on hand as back-up. They can break or burn out, or the thermostat can get stuck, always on or off. I have another two 300 watt heaters like that (Visa-Therm as I recall), stuck on Always On. I use those to preheat water in buckets when doing a WC.
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