Fluval M 200-Watt Submersible Aquarium Heater – High-Performance, Compact Heating with Mirror Technology for Fresh & Saltwater Tanks

I have a Fish Room with 39 tanks, over time my old hang on the tank heaters died and I was forced to buy new heaters. I purchased a popular brand of heaters but have had too many of them fail that I started looking for a reliable heater at a fair price. The Fluval heaters get the job done. They work like they should and so far they have lasted for me. The numbers don't align with the real temperature but I use a laser thermometer to check the temperature and adjust the heater. The heater has a blue light to let you know when it is heating.

This M series 200 watt heater is a bit overkill for my 32.5 gallon tank. But it works great!I however wouldn't rely on the temperature setting gauge on the device. The best way to properly setup a heater is to set it to come on at just the right temp you want it at. Then monitor the temps over the next few hours and raise or lower the dial to match the actual temperature you want. The dials are seldom that accurate on their own.Try to attach the suction cups near the top. Don't have the holder setting on the coil area as it can melt the plastic. Also don't let the heat bulb touch anything near it. It can damage whatever it touches and can be damaged if something is leaning on it when it turns on.Place this heater away from invertebrates and snails. They can be burned or killed if the heater turns on when they are crawling around on it.These M series Fluval heaters are good heaters and I've used different wattages of them for years. But if you use them, pay attention to your tank's temps. If they stick on, they can cook your inhabitants. If they don't turn on, your tank temp could also get too cold.These heaters also are not intended to change the temp of the tank water more than 10-15 degrees total over time. They should not be used for outside use or when the room temp is way below the temp you want your tank water. They are designed to heat a few degrees only.Be sure the glass tube is not cracked or broken. Water must not contact the inside of the tube.

The fluval 150 watt submersible heater was easy to use. The temperature was on point when set.

Have used these heaters for years on my tanks and they work well. I like the simple design and it is easy to adjust the temp, just turn the dial on the top. It is not completely camouflaged but the mirrored surface does reflect its suroundings and I like the silver color. The temp will fluctuate a couple degreees but not a big deal and expected due to temp changes in our home. The suction cups are sturdy and stay in place on the tank sides.The title of this add it says submersible, but on the heater itself it says to not submerse below this line. However I have used these for years submersed with zero problems. Fluval is a brand I trust.The size is perfect, not too long. I recenty bought the 200 watt and the length is about 10 inches. Fits nicely on the side of the tank. Another brand I bought (starts with an E) was much longer and I had to put it in diagonally. Not sure why the size is so different but I like the shorter size.The thing I dont like about this heater is that the top is too big. If I place it vertically following the directions with the dial out of the water, the top of the heater hits the rim of the tank. I like to have the dial within easy access, but it will not fit following their directions in any of my tanks. It would fit If they designed it so that the suction cup holder held the heater at more of a distance from the tank side or if they made the top narrower.Another thing to consider is that this heater has no plastic guard on the bottom. The bottom may bump on the tank sides. Both of the suction cups are attached to the plastic holder which fits on the heater, you can't change the distance between the suction cups. So if the fish swim by quiclky they can bang the bottom of the heater on the tank side. My fish are pretty big and can hit it petty hard- they have shattered the bottom of every glass thermometer so I switched to digital. Tried sliding the holder further down but the holdef fits too loosely and the heater is top heavy, so I added another suction cup at the bottom of this heater just to be safe.For the price I think this a good heater.

The media could not be loaded. Here's how I have mine hidden and what it looks like. Don't mind the driftwood tannins, they like it. Adjustment was easy, and the mounting suction cups/bracket are great. The cord is somewhat flat too. There is a dim blue light that illuminates when it's heating, i have it positioned so I can just barely see it, at least when my curious Cichlid isn't in the way. 🙃If you happen to have a chrome theme in your tank, this would only add to that vibe!

I used Amazon to purchase my second Fluval 100w submersible heater, because it was a better price Tha PetSmart.My first one, I purchased at a local pet store about 6 years ago, and didn't fail me once. My original heater was used everyday, not once was it turned off, except with water changes and other maintenence. It kept my tropical fish warm and happy year round at 72°.I never realized that the heater was not fully submersible, just to the two water lines...my original heater I kept just about dully submerged in my tank, but never had any issues in doing this. The only problem I ran into, eventually I could not read the temperature gauge for the dial anymore because it came off or become covered in algae. My new one I will be sure not to fully submerge it, but it will still be over the water line, otherwise it wouldn't fit under the hood.I could have replaced the heater sooner, and wish I had...the week before my old one broke, I had put it down on the list of things to get. Pretty lucky that the heater didn't hurt any of my fish when it busted, it just ended up cracking, and the bottom fell off. This doesn't falter decision on my rating though, the heater lasted longer in my tank than any other I have used in the past, and I have kept aquariums for about 15 years now.