Tank Layout

[Jules H-T]

Just make sure that the heater and the thermometer are in high flow areas, and not on top of each other.

I'd do it heater by the filter output, and thermometer by the filter intake. This will ensure that the cooling effects of the filtration process (from going through thin tubes exposed to cold air) are negated as soon as the water gets back into the tank. It will also ensure that you are measuring the temperature of the tank in general rather than in a particularly warm or cool spot.

Don't stick the thermometer by the filter output, you could well end up with a tank temp higher than the thermometer reads without ever knowing, since the water coming back in from the filter is likely to be cooler than the heated tank water.

Don't worry about the orientation of the filter, it's irrelevant IMHO.

With decor, just make sure that nothing creates totally dead spots in the tank with no flow. It is no good having the filter output aiming straight into a cave, and the flow going nowhere. With a hex tank I would try and get a whirlpool type flow if that's possible with the filter output (not a raging torrent like you've pulled the plug out of a bath, just smooth rotary flow).

Edit: Just for the sake of splitting hairs (since with decent flow it'll be irrelevant), don't you think that heater horizontal at the bottom will keep the top of the tank's temp too high, since the thermostat on the heater will not be measuring the temperature of the heated water (since it's all headed upwards)? Much much more important is to keep it in a high flow area to ensure the heated water gets distributed effectively.

 

[annka5]

Edit: Just for the sake of splitting hairs (since with decent flow it'll be irrelevant), don't you think that heater horizontal at the bottom will keep the top of the tank's temp too high, since the thermostat on the heater will not be measuring the temperature of the heated water (since it's all headed upwards)? Much much more important is to keep it in a high flow area to ensure the heated water gets distributed effectively

... But it would be almost impossible to have your tank so still that that could ever happen. I agree the heater should have a decent flow of current around it - but that had already been said when I added the comment re: heater orientation.
Nah, I stick with my statement - heat rises so whould put heater toward the bottom and horizontally.

 

[Jules H-T]

... But it would be almost impossible to have your tank so still that that could ever happen.

So you acknowledge that since the flow is there, it's irrelevant. Certainly not worth worrying about. Putting it horizontal in a hex is going to be major hassle, considering the width of each panel is likely to be shorter than the heater. So I wouldn't do it on that count alone.

Nah, I stick with my statement - heat rises so whould put heater toward the bottom and horizontally.

OK. I'm in one of those moods today, sorry. The inital request was for logical theory, so I feel vindicated in following this up!

Assume no flow, so there is a point to the discussion!

Assume the ambient temperature is 72 degrees. The heater is set to 76.

Assume the following scenarios:

(1) You have the heater dead horizontal. The heater is therefore on. It heats the water which rises straight up since it's at 76. The thermostat doesn't feel this since the water is gone, so it stays on. More heated water rises, but the bottom of the tank is still cold. By the time the water at the bottom is at 76, the water at the top will be a good 80+.

(2) You have the heater at a 45 degree angle, pointing downwards, element at the bottom and thermostat at the top. Same ambient and heater settings. The heater heats some water, which rises. The thermostat, which is around the middle of the hight of the tank, switches off when the middle of the tank reaches the desired temp- the top will be marginally hotter, the bottom marginally colder.

(3) You have the heater pointing straight down. Same settings. The heater heats some water, which rises stright to the thermostat, and the heater switches off almost immediately, leaving the whole tank only just above 72.

Anyone disagree with the logic? Which would you chose? I always have, and until I hear a convincing arguament otherwise always will, put my heaters at a 45 degree angle, pointing downwards.

Absolutely no offence intended, and you can do what you like, I just had a spare 10 minutes to play with

 

[Notsofab]

I'm in no position to agree or disagree with anyone.

All I do know is that my heater thermostat is set at 25 degrees and my thermometer which is on the opposite side of the tank and a bit lower down than my heater is reading a steady 24.8 degrees. So I think I'll just leave things as they are for now and keep if monitored as the fish go in.

 

[annka5]

a) You have the heater dead horizontal. The heater is therefore on. It heats the water which rises straight up since it's at 76. The thermostat doesn't feel this since the water is gone, so it stays on. More heated water rises, but the bottom of the tank is still cold. By the time the water at the bottom is at 76, the water at the top will be a good 80+.

.. but the heat isn't going to rise up instantly in a dead straight line..... if you've a radiator in your living room, the heat still rises, but you can still tell your heater is switched on (i.e. feel the warmth of it) when you're sat in your armchair a distance away. You wouldn't say there is a "current" or rather a draught in your living room though.

HOWEVER, I actually agree that more therms would be going to the top, but this is a good thing because the heat is going to escape into the air space above and into the room....surely more will be lost from the surface than anywhere else, simply because of the insulating qualities of air/non-airtight aquarium lid/ sealed glass.

No offence taken... except I really should do some work today!

Notsofab, you're just boring and sensible not getting sucked in to the debate! Too groan-up by far.

 

[Jules H-T]

except I really should do some work today!

You and me both. I honestly cannot be arsed though.

Ps. Check the position of your central heating thermostat- I think you will find it is half way up the wall, to measure the average temperature in the room

 

[annka5]

Actually, my central heting thermostat is in the stupidest place in the world, right beside a very old very draughty skylight. Ha! so there goes that theory.... no, I s'pose it should be half way up a wall, but, erm, is that not jsut to keep your shoulders warm?! (no, don't answer that)