Need a Heater for Platy Fish?

Topic: I just bought my first aquarium. Do platy fish need a heater? What heater do I buy for a 20 gallon tank? Is it specific or will any heater work? Does the platy need warm water? What water temperature should I keep my water.. should I keep it that temperature at night too?


*Awarded Answer
Posted by Chelsey K: It’s good that your trying to take proper care of your new fish! Platy fish do need a heater in their tank. When buying a new heater figure on needing 5 watts of energy per 1 gallon of aquarium water. You need your water temperature to stay in the range of 74-82 degrees Fahrenheit.

All tropical fish need a heater and that’s most of the fish that pet stores sell. So it’s better to just buy a heater and that way you can get a bunch of cool tropical fish to keep together. Here is one of the most highly rated heaters on the market. It also ships with the Amazon prime fast shipping. I highly recommend this setup.

Some heaters that you buy don’t need to be set.. all you do is put them in fish tank and they automatically do their job. Just remember that you want your water temperature between 74-82F.


Should I Fully Submerge Aquarium Heater?

Posted by Allison B: How many of you don’t fully submerge your adjustable heater? I keep the temp knob just above the water because putting an electric device completely under water makes me nervous!

  • Understand your concern. But I’ve been fully submerging heaters for years and years. No issues.
  • I keep mine as low in the tank as I can so when I do water changes it never comes out of the water.
  • Having a technical background, I keep mine above the water, yes I know it is supposed to be safe, but better safe on my end than sorry.
  • So after I sent over my reply, I just realized that I have a slim marina HOB and the silly little pump is submerged in the tank along with the wire. How stupid do I feel now.
  • Most heaters have a minimum water level marked on , I’ve always fully submerged heaters and never had a problem.
  • the only time i have had a problem submerging a heater was with a 200w aquaone unit (the instructions stated that it was meant to be placed in the sump , under water)… leaked and blew after 10 days, its replacement did the same after about 8 hours..
  • They’re designed too be fully submerged…you run the risk of it blowing out the water…I made the mistake of forgetting to switch it off during a water change and blew one once…
  • I did that once too. I make sure that the glass is fully submerged. I had forgotten to turn off the power strip, and when the tank was about half empty heard a sharp crack. Grabbed the heater, and the glass had cracked in an even line exactly where water met air at that moment. Fell off cleanly, by this time I had it turned off so nobody got zapped.
  • I know that it’s silly and if it wasn’t for the access situation I’d bite the bullet and submerge but I like to be able to adjust. My house temps range on a daily basis from 55 to 70 (rarely) so I do have to adjust my thermometers. Especially the one next to the window (which gets insane plant growth by the way).
  • Ur plants are growing well because of the natral light and heat. My manual on my heater is to have it under water & mine is perfect and temp is perfect for what i need it at & keeps it warm and soon as it cools the heater comes on stright away. Brilliant heater & no problems so far.
  • I have mild winters, the temps only change by about 10 degrees at most from my summer temps. The heater does compensate, but I like to keep an eye on things.
  • It’s probably 60 at my house now. On Christmas, it’ll probably be about 50 degrees. Lots of rain though. Pelting, driving, sideways, hurricane force winds rain.
  • I have the opposite- autoimmune reactions to temps over about 64 for extended periods. So I keep my house cold and I am blessed to live in a place with no summer heat at all.
  • if its meant to be fully submersible … it should be submersed. If you are worried about electical device in your tank. Your filters are already going to pose an electrical hazard alone… potentially. Use GFCI outlets or power strips to avoid those type of electrical issues.
  • Alot of the heaters i run are external and so they connect onto the filter hose and so are out of the water completely… But, other heaters are completely submersible and ideally should be completely under the water and on an angle to spread the heat better. Once the heater is set to the desired temp, you shouldn’t need to touch it again. Always remember to turn your heaters off when doing water changes too. I know a few people that have forgotten and their heaters have blown where the water level drops below them. Although, higher end heaters have a device that will switch them automatically if this happens but its always a good idea to check. Or just knock them off if you aren’t sure.
  • I typically do 40-50% weekly water changes. Keeping theheater low in the tank on a diagonal is more convenient. I use jagers, which (once calibrated) has never failed to keep the temperature exactly where I want it, so I have no need to fiddle with the dial.
  • I used to, but kept forgetting to turn it off during changes, learned about them exploding, and have fully submerged them since! I keep them by water flow, to circulate the temp better.

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