I recently changed my heater to a 100 watt instead of a 125 watt, i have maybe 40 gallons is im heating. Its a eheim heater i set it to 78 degrees. I was shocked because other days it seems to be able to heat the tank. I ramped up the heater to 81 so it starts heating but i have an inkbird set at 78 to shut it off. Should i change back to the old heater and buy a ne 125 watt? Or will the 100 watt be fine. Corals look fine i just dont want to kill my sps. Maybe it was a calibration error on the ehiem?
Temperature dropped 3 degrees
- Thread starter Fishko
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Where are you located? If your in a cold northern basement 100 watt is a bit on the light side and if you're in Orlando, FL 100 watt is overkill.
With that said 3 degree swings in temperature happen on natural reefs so I wouldn't expect it to hurt your coral if it happens on a rare occasion. Run the 100 for a week and see if the temp settles in or if its struggling to maintain.
With that said 3 degree swings in temperature happen on natural reefs so I wouldn't expect it to hurt your coral if it happens on a rare occasion. Run the 100 for a week and see if the temp settles in or if its struggling to maintain.
Lovefish77
Well-Known Member
I personally dont trust on board heater thermostat, I have separate 2 way controllers on both of my tanks.
Im in illinois, suburb near chicago. 125 watt kept my tank up perfectly, idk why i decided to buy a 100 watt this year. Wanted to pull less power. Cause its a 29g display and 10g sump so probably more like 34 gallons if we take out the sand and rockwork.
Brett S
Valuable Member
It really depends on the ambient air temp around the tank, rather than the location. If I blast my AC and keep my house at 65 here in Orlando then I’m going to need a bigger heater than someone in IL who keeps their heater running and keeps the house at 78.
Certainly it’s likely that colder climates will have lower ambient air temps and warmer climates will have higher ones, but rather than look at the location it makes more sense to look at the actual temp of the air around the tank.
of course ambient temp plays a huge roll but generally the colder the region the bigger the heater needed, as most people don’t have the heating on 24/7.
I still think a 100w for a 40g is a little under powered.
I see where you are coming from, the 125w was able to heat my tank well. It seems to be heating up however. We dont run heat at night. If the 100w doesnt work out ill use it in my qt system in the basement. I think the problem is my return is 185 gph and and is a little slow to turn over the sump quickly. Im probably going to upgrade the sicce and use the old one for salt mixing
Since you use an external temperature controller and don't rely on the internal thermostat on the heater, I would turn the heater to 81 and see how it does.
Those Ehiem heaters are consistent, but they need to be calibrated before they are accurate. I would not be shocked at all if your 78 on the dial is really 75 prior to calibration.
I have a 135G with a 50G sump, I use a 300W heater, and I keep my house at 68 degrees (about to be 65) in Oklahoma and it does the job just fine. My return can't be more than 4x the tank size either, it's a DC Pump and I have it on speed 1. I have my Apex set to 77 and the heater set to 80ish in case the apex ever fails.
Whiskey
Those Ehiem heaters are consistent, but they need to be calibrated before they are accurate. I would not be shocked at all if your 78 on the dial is really 75 prior to calibration.
I have a 135G with a 50G sump, I use a 300W heater, and I keep my house at 68 degrees (about to be 65) in Oklahoma and it does the job just fine. My return can't be more than 4x the tank size either, it's a DC Pump and I have it on speed 1. I have my Apex set to 77 and the heater set to 80ish in case the apex ever fails.
Whiskey
Lovefish77
Well-Known Member
Yes a two inkbird or something else with one switch for a heater and another for a fan.
Sadly today i noticed the temp dropped again at night. I added back the second 125w heater set at 75 degrees to the inkbird as a backup. Should i buy a another 100watt heater and replace the 125 watt thats a year old in there. So that there would be 200 watts in total but one is set at 75 and other at 78 to keep things stable in winter and just remove one in the summer?
I think your issue is that one heater is not enough to raise the temp from 75 to 78, I had the same issue, tank temp I wanted was 79 I was using two heater but one of them was an Eheim preset heater that could only be set to 77f so the tank would drop temp, I changed the preset heater to a normal heater set at 79:and the tank is fine now.
Brett S
Valuable Member
I think two heaters is fine, and frankly there are advantages to having two heaters, in that if one fails then the other will at least be able to keep the temp from dropping too much.
I wouldn’t set one to 75 and one to 78 though. You already know that one heater is struggling to keep the temp above 75, so why do you want the second heater to turn off at 75? The tank will still have big temp swings because the one heater that’s still running won’t be enough to keep it at 78.
