we have a 4 foot tank approx 200L, we have problems maintaining the temperature we have bought 4 heaters different brands all 300w, set on 28oc, turns off at 23oc,we have two thermostats both read the same cant figure out whats going on , surely we cant have 4 faulty heaters, turned temp up to 30, but no diff still only gets to 23, any ideas HELP

where are you putting the heaters?

They need to be in a position where water is flowing through it so it heats the water as it passes by, this way warm water is distributed evenly throughout the tank.

But say if your heater is in a position of very still water and the thermometer is on the other side of the tank, then you are going to get a warm end and a cold end.

The heater automatically detects the temperature of the surrounding water, in the case above the surrounding water will be the degree you have set but the water far away from the heater is still not quite warm enough.

Hope this helps.

Also there is a problem where the heater element affects the temp that the thermostat is seeing. I try and put my heaters at a 45 deg angle so heat rising from the element doesn't directly flow over the thermostat part. That and having a good water flow past the heater seems to do the job.

Set the heater and leave it there overnight and see what the tank settles down to, then adjust the temp up and down a few clicks to suit. Dont worry about the exact temp the element switches on and off, thats affected by the proximity of the element. But after 12 hours or so it should settle down to a steady temp.

Cheers

Ian

my community tank is around 200L. i have a 150watt heater at each end of the tank, on a 45' angle & at the bottom. with the flow of my tank the two heaters heat more evenly than one heater.

what thermometers do you have and where are they compared with the heaters?

Maybe it's your thermometer that's reading incorrectly.

Test your thermometers, take them out, put it in your cold tap water or something, tap water should come out at about 10 degrees.

Hummingbird has a point, if it's a faulty thermometer no point wasting your money on all the heaters.

But very unlikely it's the faulty thermometers, never heard of a faulty thermometer, chances are even lower when you have two reading the same value.

my community tank is around 200L. i have a 150watt heater at each end of the tank, on a 45' angle & at the bottom. with the flow of my tank the two heaters heat more evenly than one heater.

i have set my heaters up in the same way. do not go off your thermostat indicators on the heaters. i have learnt that most of the time these are wrong. set the heaters differently ie. hotter on the heater thats closer to the outflow from your external filter if you are using one. for example i have set my heaters at 27-28 degrees on the heater that is closest to the flow and 25-26 degrees on the other end of the tank. rely on your thermostats that are independent of your heaters ie totally separate thermostats.

my tank sits at a regular 25-27 degrees constantly. its only a 230-240lt (roughly) tank. this set-up works for me. don't rely on 1 heater for such a long tank tho.

thanks for the feedback with the heater problems, we have moved the tank back inside as was in the garage due to getting carpet laid, holding temp better maybe too cold outside

But very unlikely it's the faulty thermometers, never heard of a faulty thermometer, chances are even lower when you have two reading the same value.

It happens, i had TWO faulty thermometers about a month ago. One hailea digital which gave readings which was 5 degrees warmer than the actual temp and one mercury which had a small hole in it causing the temp read out to be about 5 degrees warmer than it actually is. i now run at least two thermometers in each tank to make sure the readings are accurate