Have you guys had issues with build up, on your heater surface, on hard water tanks???

The issues I had keeping the tilapia tanks warm, with that early cold spell last fall, turns out to be because the heating surfaces were all coated with a honeycomb blanket of calcium, algae, and fish poop… with the plastic guards, it wasn’t easy to see, but was a full 1/8 inch thick of insulation, baked on the glass tubes… I’m trying not to throw them away, so I disassembled the plastic, and hand scraped the glass tubes, on the 1st one, on the 2nd one, same issue, I found a container (not quite big enough) but filled it with vinegar, and it’s fizzing away right now… I’m hoping I can just rinse it afterwards, rather than disassembling it

Just curious if this ( worse than I’ve ever seen ) was related to the heaters running hard, the algae, from being outside, or???

I’ll be keeping an eye on them, this year, and hopefully the vinegar trick works, for cleaning, as needed

The chunks pretty much fell off, but I still had to remove the guards, after soaking heater 2

Heater 3 is soaking now… 1 and 2 are heating the big tanks over night, even though it’s mid 80’s outside air, the tanks in the shade were 71 degrees, when I installed the heaters… pictures of #3, before soaking

Heater 3, actually built up so much on the glass tubes, that it built up pressure on the guards, and broke the glass tubes… 1st picture here shows the guard being forced apart in the seam

I am trying a few Titainium guard less heaters this year, and in the time it took to bring the temperature up, on the 275 gallon tanks, they were already getting a film of calcium on them, with no fish, or algae in the tank, so likely I’ll need to clean them every couple weeks…

I would tend to believe that it is the guards that is the problem. I have PH 8.3 with KH and DH way over 300 ppm. I have had heaters in some tanks for close to 10 years and have never seen buildup like that. Either the guards or you need to get a different kind of heater.

I’m wondering if it’s a combination of hard water, and the small green algae, that stays waterborne… but I do have a rust film, on 2 new heaters with clean water and no fish yet, which makes me feel maybe it’s the surface area of the heating surface, in relation to the volume of the tanks… these are 800 watt double tube heaters… it’s probably a minimum for the size of the tank, and being outside… perhaps a bigger surface area, wouldn’t push the heaters so hard, or putting more heaters in… maybe 8 - 100 watt heaters, would perform better than 1 - 800 watt heater???

OK didn't realize the heater was that big. The biggest I have is 250W. If you have well water I suspect the heaters are burning the calcium/lime in the water onto the glass. I have that problem with my water heater, but that is a 4500w heater so not to applicable to your problem. But it says to me that the higher the heat, the more buildup. I am no expert but I suspect that maybe something like 3-300W would work better than the single big one.. Worth a try if it is within your budget.

I have had calcium (in freshwater) and coralline algae (in marine tanks) build up on heater glass. I just scrubbed it off with a sponge that had the green scourer on one side. Soaking in vinegar does the same thing but with less effort.

The heater guards tend to trap a lot of gunk and that makes it worse than a heat without a guard.