For some reason the heater in the 125 gallon oscar tank is no longer working. It doesn't heat up! The temperature is currently hovering around 66 degrees fahrenheit.

Is there a way to repair the heater? If not, what is the cheapest and most efficient heater that I should buy? The current heater is a 300 watts one.

Don't bother repairing. Buy a new one, and quick.

wow! quick response. what is the ideal wattage? wouldn't a tiny heater work but it just takes a bit longer to heat up the tank?

i have not use any heater yet since i am in a tropical country
but i believe there is a level indicating how many gallon should
be for every WATT capacity. and i suggest look for the one that
is auto off when not submerge in water to avoid accidental burn-out.

i buy rena smart heaters 300w they are UNBREAKABLE made from parkerized metal with a ceramic core they are the most accurite and effective heaters i have EVER used and the 300w only cost me £25 on ebay brand new.........untill you get one fill a hot water bottle you use for bed years ago with boiling water and put it in the tank....in the morning.... your tank will keep a temp of around 80 all day then remove it refill it with more boiling water and put back in last thing at night to take the tank through the night .....this has worked for me my father and grandfather for years and years actually going back to the 1930,s and is still an effective method of keeping temp up in colder climates with power outages ........

biggamehunter wrote:


i have done this myself during a 2 day power outage we had here a couple years ago.(ive since bought a generator just in case it happens again).

as for heaters i use eheim jager heaters and have nothing but great things to say about them. they arent unbreakable like the rena but still a great heater.

Remember that if you have a large tank with a small heater, the heater will be on all the time trying to heat the water up. so in the long run, it will probably pay to have two larger heaters that aren't on all the time. Also, it's always a good idea to have a backup in case one breaks. This happened to me recently.

I thought I would also mention that if you are using heaters in a sump tank that is tucked away in your cabin, make sure you keep an eye on the heater and make sure that you clean off any algae. Algae will grow on the heater and can act as an insulator which in my case, resulted in the heater breaking due to overheating.

I can't seem to locate any heater that is made for 125 U.S. gallons. 300watt heaters are rated for up to 105 US gallons..

a 300w will do a 125 fine

biggamehunter wrote:



How does the rena smartheater hook up to the rena filter system? It seems like a really cool heater.

the inlet fits down inside the heater and the new intake strainer is the bottom of the heater ....it has grilles on it and a hollow tube in the casing ,it will work with any external fiter......the heater body fits whare your intake strainer was

biggamehunter wrote:


Do I need to buy any extra materials to connect the heater with my renafilstar? I'm a bit afraid the tubing won't fit.