question on tank temps

[Kaga's Kritters]

I have noticed the water at the top of the tank always feels warmer than lower down so i stuck a thermometer at the top to see what the temp is up there. The temp in most of the tank (middle to bottom) is 71.7 F but the temp at the top is 88.3 F. Why is it so hot at the top? Is it from the tank light? I just have a regular hood on it with a PowerGlo 20watt strip light in it. Is it ok for the temps to be like that? My gouramis are usually at the top, so I guess they like the warmer temp. I have a lone tetra in there that stays at the bottom most of the time. My 2 yoyo loaches don't seem to mind the cooler temps at the bottom either. i would like the temp in the middle to lower to be warmer, but i cant seem to get it much warmer. I have my heater set at about 82-84, but for the most part the tank stays like 71-72. I did have the heater laying on its side (stuck to the wall of course) near the bottom of the tank. Today i put it upright and right by the filter intake. the temps in the tank were like this before i moved the heater and are still like this, so i dont think the position of the heater is the prob.

[doug z]

My gouramis are usually at the top

No, they normally dwell at the top of the tank..

Sounds like you're not getting enough water circulation..

What are you using for filtration?

[Kaga's Kritters]

i have an Aqua Tech 20-40 filter on the left side of the tank and then on the right side i have a 12" bubble bar in the gravel (goes longways left-right).

[rageybug]

The warmer water in your tank will always be at the top (heat rises) and your light will also contribute to the warmer water temperature at the top. You may want to look into a small pump/power head to better circulate your water and even out the temperature a bit.

[tropfish]

The light is probably heating up the thermometer, but as long as u have adequate water movement it's no big deal.

[doug z]

i have an Aqua Tech 20-40 filter on the left side of the tank and then on the right side i have a 12" bubble bar in the gravel

That should be adequate, if the bubble bar is on all the time..

Just make sure you're thermometer is on the opposite side of the tank from the heater and in the middle of the tank, and you should be fine..

[Glub]

Have you recently added any new water to the tank?

Cold water is denser (and heavier), so it will always sink to the bottom. Water does not instantly mix. The cold water needs time to be warmed up by the water around it so it becomes less dense and mixes into the water around it.

The result of this is that instead of the colder water you poured in mixing instantly, the cold water will sink and form a layer on the bottom of the aquarium with a temperature line between the warm and cold water.

Really cool experiment for you to try (it looks cool to). Take a bit of food colouring and add it to a glass of ice water, and gently pour some into a cup of uncoloured room temperature water, careful not to stir or aggravate the water too much while you're pouring it, and watch as the coloured water slowly sinks and settles on the bottom as it diffuses into the warmer water. This way you can actually watch what I suspect may have happened to your aquarium.

Also any heat of course will rise up to the surface, so this may be the cause as well.

Maybe position the heater horizontally along the bottom rather than vertically on the side to allow a wider area of heating starting from a lower depth to help maintain a more constant temperature between the surface and the bottom. Remember, heat naturally travels upwards, not sideways and down.

[Kaga's Kritters]

Have you recently added any new water to the tank?

Cold water is denser (and heavier), so it will always sink to the bottom. Water does not instantly mix. The cold water needs time to be warmed up by the water around it so it becomes less dense and mixes into the water around it.

The result of this is that instead of the colder water you poured in mixing instantly, the cold water will sink and form a layer on the bottom of the aquarium with a temperature line between the warm and cold water.

Really cool experiment for you to try (it looks cool to). Take a bit of food colouring and add it to a glass of ice water, and gently pour some into a cup of uncoloured room temperature water, careful not to stir or aggravate the water too much while you're pouring it, and watch as the coloured water slowly sinks and settles on the bottom as it diffuses into the warmer water. This way you can actually watch what I suspect may have happened to your aquarium.

Also any heat of course will rise up to the surface, so this may be the cause as well.

Maybe position the heater horizontally along the bottom rather than vertically on the side to allow a wider area of heating starting from a lower depth to help maintain a more constant temperature between the surface and the bottom. Remember, heat naturally travels upwards, not sideways and down.

i did at water change today......but the temp in the lower part is still the same as it always is, and if you stick your fingers in the water at the top it always feels really warm. as i said before, the temps have been different for awhile now.

the heater had always been laying flat near the bottom in the middle of the back of the tank. the water was still different temps that way. i moved the heater today, it is vertical but still close to the middle of the tank and on the back wall. so even with it horizontal near the bottom it didnt make the temps any better

my 10 gal is not like this at all, the temp is pretty constant throughout the water in it. its just my 29g that is having the prob.

do you think it may help if i moved the bubble bar to sit crossways (front to back) of the tank instead of side to side? (it is currently side to side, opposite side of the filter, about 2 inches from the back wall)

[Glub]

Honestly, I have no idea.

I think the earlier suggestion of getting some sort of pump or something to help circulate the water a little better would help.

Make sure your filter's running properly and nothing's stopping it from sucking in and moving the tank's water around.

Maybe let us know what sort of equipment you have in there that's moving the water and someone might notice something?

Sorry I can't be of more help.

[doug z]

Make sure your filter's running properly and nothing's stopping it from sucking in and moving the tank's water around.

She mentioned already that she has a bubble bar on one side of the tank, and an HOB(?) on the other..

That should be good enough, to my mind, for such a relatively small tank..

Like others have said, it's normal for the surface to be warmer than the bottom, due to the lights..

It IS a bit odd that you have such a large variance between your heater set-point and what you are getting on your thermometer..

Where is your thermometer placed?

[Kaga's Kritters]

one thermometer is suction cupped near the surface and the other has a probe you put in the water, it is at least 2/3 the way down in the tank and near the front wall on the opposite side of the filter.

[doug z]

So, near the heater?

Also, you never got back to me on wether the bubble wand was on all the time or not..

If I were in your position, and the temp varience really was as extreme as the thermometers say (NOT being a placement issue) I would have 2 HOB's on either end of the tank, the heater placed horizontally near the bottom between them, the bubblewand right below the heater, and the thermometer (the one with the probe) placed at the front right or left..

I would get the 2nd HOB over a power head..

At least with the HOB you achieve more circulation AND more biofiltration..

I would also get 5 more tetras for your lonely little guy..

[doug z]

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[Kaga's Kritters]

thanks. the thermometers are not over or near the heater. the bubble bar is on all the time. the temp at the top of the tank is just about what the heater is set on, so the heater is working, its just the warm water isnt circulating i guess. the light has been off since 9pm last night and it's now almost 8am and the temp at the top is still 86 F, so it has to be from the heater and not from the light. i will get a second filter and see if that helps. i had considered getting a second one in the past anyway. thanks for the help.

the lone tetra is a fruit tetra, yea i know, bad me for buying dyed but that is why i havent gotten him anymore friends. he did have some and they have since passed. also i am considering going to more of a semi-aggressive or aggressive tank in the near future.

[schoolbus]

Your digital thermometer may be giving a bad reading. I have one I bought online and it reads 5degrees cooler than the actual temp. Try placing the suction cup thermometer lower in the tank and see if the water isn't warmer.

[Kaga's Kritters]

Your digital thermometer may be giving a bad reading. I have one I bought online and it reads 5degrees cooler than the actual temp. Try placing the suction cup thermometer lower in the tank and see if the water isn't warmer.

i read your post soon after you posted it and moved the suction cup thermometer down to the bottom of the tank. it's been down there for about 1 hr now and is reading 85 F. So the water is warmer down there. the other thermometer is just crap, lol. the other one i was using was a coralife digital with the long probe. I took it out of the tank and now sitting in the house it is reading that the room is like 46 F! It's actually like 75 F in here. So no wonder i was getting odd readings. wow! I think I am going to put the zoomed suction cup thermometer in my 10gal for alittle bit to make sure the coralife in that tank is working right. thanks for all the help!

i still may get a second filter for the 29gal just for the extra filtration too.