Jestersix

Heater controller question

Da_Neefer

Da_Neefer

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I'd like to run a pair of 200w titanium heaters for redundancy vs just one bigger heater. I currently have an eheim 300w heater connected to a Bayite temp controller. Do most of you running dual heaters run a pair of temp controllers or connect both heaters to one temp controller? I'm not running an Apex/GHL controller if that makes a difference to the answer.
 
I would run them on separate controllers. Running them on one, you really lose half the redundancy. If a heater fails (off) you still have the second running, but if the controller fails, you're in the same spot as having just one heater.
 
I would be willing to use one controller, but I would not be willing to use a heater that does not also have a built in thermostat, even on a controller. I don't know which titanium heaters you have in mind, but many have no built in thermostat. I've seen a couple tanks crashed due to heater stuck on, but I've yet to see one crash due to heater stuck off. Sure the coral gets unhappy, but I've seen an SPS tank that spent a week at 70 *F. The coral wasn't happy, but nothing died and you will notice the instant your hand goes in the water. On the other hand, if you tank spends 24 hours at 92 *F, there is a high likelyhood of a full crash, or at least heavy losses. Even if your house is cooler than 70 *F, the pumps, lights, etc. will keep things a bit warmer than that (this depends on your evaporation rate and if you have lids, but it tends to be close).

Running 2 smaller heaters instead of 1 larger one has 2 benefits:
1. If one fails you still stay sort of warm.
2. If one gets stuck on it takes longer to cook the tank. If you run 2 that are full size, or close to full size, you lose this benefit.

The failure modes I've seen with a temperature controller running a non-thermostat heating element are:
Temperature controller probe is in the display, heater is in the sump. The return pump fails or is shut off for a long time due to maintenance. The display gets cold because it has no heater, the controller tries to warm it up, and the sump gets cooked.
Temperature probe ends up not in the water. This might be because the water level gets low in the sump exposing the probe, the probe cord getting pulled lifting the probe just above the water level, or the probe completely falling out of the sump. Now the controller thinks the air temperature is actually the water temperature. Because our houses tend to be cooler than the aquarium temperature the heater is effectively stuck on!
Both of these scenarios are avoidable by using heaters with built in thermostats (like your Eheim) and leaving them set just a degree or two above your target. If your controller ends up incorrectly on (programming issue, hardware failure, or one of the issues above) then your tank runs a couple degrees warm, but doesn't overheat.
 
Thanks for the thoughts! They are much appreciated. I've never run a dual heater setup before so I thought I'd ask.

I'm waiting on a pair of 200w BRS titanium heaters to be delivered along with a 2nd temp controller. Now I'm debating returning the BRS heaters for a pair of eheim 200w heater even though they are longer.
 
That would be my preference, at least for the heating elements. Larger has some perks, among others it means the surface temperature doesn't have to be as hot to move the same amount of heat. I wonder if this means the internals last longer, but that starts making a lot of other assumptions. Your other option would be to use a pair of 150 W heaters instead of a pair of 200 W heaters. In the case of the Eheims the 150 W model is 2" shorter than the 200 W model. If your 300 W heater kept things warm, the pair of 150 W heaters would too. Not as fast a recovery if you do a cold water change though.

Seeing as you'll have two controllers, I would put at least one of the heaters (and controller probe!) in your display if there's an acceptable way to do so. This way you still have a heated display if your return pump fails. Having a heater in the sump and a heater in the display is dependent on having the second controller, or blindly trusting the internal thermostat on the heater.

Horizontally at the bottom rear behind the rock stack is an easy way to hide a heater, and inside the overflow box is another. The latter of course requires a tall enough standpipe that the heater stays submerged when the return pump stops.
 
jccaclimber said:
That would be my preference, at least for the heating elements. Larger has some perks, among others it means the surface temperature doesn't have to be as hot to move the same amount of heat. I wonder if this means the internals last longer, but that starts making a lot of other assumptions. Your other option would be to use a pair of 150 W heaters instead of a pair of 200 W heaters. In the case of the Eheims the 150 W model is 2" shorter than the 200 W model. If your 300 W heater kept things warm, the pair of 150 W heaters would too. Not as fast a recovery if you do a cold water change though.

Seeing as you'll have two controllers, I would put at least one of the heaters (and controller probe!) in your display if there's an acceptable way to do so. This way you still have a heated display if your return pump fails. Having a heater in the sump and a heater in the display is dependent on having the second controller, or blindly trusting the internal thermostat on the heater.

Horizontally at the bottom rear behind the rock stack is an easy way to hide a heater, and inside the overflow box is another. The latter of course requires a tall enough standpipe that the heater stays submerged when the return pump stops.
Click to expand...

It's 100g total system water volume with a "68g" display. Normally the room temp is 68 degrees or higher so the tank really requires minimal heating unless my room heater happened to fail. 150g of water heated to 77-78 degrees really keeps the room rather on the warm side anyway. I could probably hide one heater behind the rock work at least from the front view. There are a few pics of my display in my build thread to give you an idea but to be honest I'd rather keep the heaters in the sump if possible. The overflow is a eshopps medium on a rimless tank so that's no help.
 
I always recommend 2 controllers/thermostats per heater. One can be the built-in thermostat. Mostly protecting against a fail-on scenario. This is worth getting right because it’s probably the top reason for tank crashes.

I give more details on my approach here:

JVU’s RSR750

I like the zoa Alcatraz, I guess the inverted cone shape keeps them on the rock? You just have to deal with the ones that free-float once in a while? So are your heater elements plugged into your Inkbirds, which are plugged into the Apex? This is how I set mine up, using Apex as the kill switch...
bareefers.org
 
I run 2 heaters into an Inkbird and the Inkbird into my Apex.
The heaters have their thermostats set to desired temp, same with the inkbird.... if both the internal thermostat and the Inkbird "fail on" the Apex will just shut everything off at 81 degrees and alert me.
 
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