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I'm setting up a breeding tank for my Discus and need advice on heater placement. The tank is a 40-gallon breeder, bare bottom, with a sponge filter and a few Java ferns. I've got an Eheim Jager 150W heater but not sure if it's better to place it horizontally near the bottom or vertically in the back corner. Water temp is currently 82°F, aiming for 84°F. Any tips?

I've had good luck with horizontal placement near the bottom for even heat distribution. Just make sure it's not touching the substrate or any decor. What's your water change routine like? Frequent changes can mess with temp stability if the heater's not dialed in right.

My heater's vertical but now I'm wondering if that's why my temp fluctuates. Tank's 30 gallons, same setup as yours but with a canister filter. How often do you check the temp?

basis wrote: ↑Sun Jul 06, 2025 5:46 am I've had good luck with horizontal placement near the bottom for even heat distribution. Just make sure it's not touching the substrate or any decor. What's your water change routine like? Frequent changes can mess with temp stability if the heater's not dialed in right.

Thanks for the tip. I do 50% changes every other day with aged water, so stability's a concern. Gonna try horizontal and monitor.

Aged water's smart. I'd also recommend a backup thermometer. Those Jagers are reliable but it's sketchy relying on just one device when breeding. My pair spooked last time the heater stuck on, lost a whole clutch.

Yep, learned that the hard way too. Now I run two smaller heaters instead of one big one. If one fails, the other can kinda cut it. What's your pH? Mine's around 6.8, seems to chill them out.

micsim wrote: ↑Sun Jul 06, 2025 11:35 am Yep, learned that the hard way too. Now I run two smaller heaters instead of one big one. If one fails, the other can kinda cut it. What's your pH? Mine's around 6.8, seems to chill them out.

Two heaters is genius. My pH is 6.5, soft water. They're less jumpy when it's lower, but gotta watch for crashes.