Can't keep temperature stable throughout tank

[Flubberlump]

Tank size - 25ltr (~6.5gal) planted
Ammonia - 0
Nitrite - 0
Nitrate - 10-20
pH - 7
Temperature - should be 27C throughout
Inhabitants - 1 male betta splendens, 3 Sulawesi snails
Plants - bacopa amplexicaulis, cryptocorne moellmanii, Anubias nana mini, dwarf hairgrass, water lettuce

I have a 25w heater which should be ok, but I can't get the temperature stable throughout the tank. I have it stuck diagonally in the middle of the back of the tank. When I put my hand in this morning when cleaning the tank out there was a several degreeC difference about 3" from the bottom of the tank. I'm talking a noticeable difference, it was cold at the bottom! I reckon not much above 20C if at all. I've been wondering over the last few days why the snails haven't been going to the bottom - that'll be why.

What can I do? I have low flow from the filter (little internal canister that came with the tank) because of the betta and obviously can't increase it very much but there seems to be no water movement at the bottom of the tank. There must be little, if any. I've moved the filter onto the side of the tank so that the flow is blowing across it to try to circulate the heat but it won't make any difference to the bottom. The rest of the tank is even. Should I move the heater so it's as close to the bottom as possible? The betta is swimming around fine but I can't keep the snails like that and need to sort it asap. The snails were using the bottom until a couple of days ago when the weather got colder and the room temp drops now, especially at night.

Thanks in advance.

 

[Ch4rlie]

Can you put the heater horizontal nearer the substrate? That way heat may be better since heat rises but betta tanks do often have low or poor flow which does contribute to fluctuating temps throughout the tank.

Snails should not be too bothered about temps esp if around 22 -24 at the lower areas of tank I would have thought, so that behaviour is a little strange. But of course if it's really cold then that's makes more sense.

 

[Flubberlump]

Good point I'll try putting it horizontal at the bottom and see how that goes. The filter has very low flow, it's only small but I crammed it with sponge from my other tank too so maybe that's decreased it even more.

Rabbit snails need warmer temperatures though don't they? 26C upwards I thought.

 

[Ch4rlie]

Ah, have just been having a look online regarding Sulawas Snails, you are indeed correct that these snails prefer warmer waters, 27 - 30C.

"If kept at suitable temperatures of 27-30°C/81-86°F, they are the largest imported water snail compatible with tank keeping. They even reproduce in the aquarium." according to Practical Fishkeeping.

Snails from Sulawesi - Practical Fishkeeping

So having your tank at optimal temperature is even more crucial, not just for your betta. Perhaps the first thing to try is to have that heater in horizontal position about half to an inch above the substrate, see if that helps any.

And maybe if you have a spare thermometer, have one at the bottom of the glass and one miday to top of glass, that way you can have a more accurate picture of how your tank is doing regarding temperature wise.

Then we can start to take it from there.

 

[thrujenseyes]

This is going to sound really silly but could those larger rocks at the bottom be holding onto the cooler temps making it feel colder at the bottom?! Rocks hold heat or cold for a while...just a random thought.

 

[Ch4rlie]

I suppose thats possible, never thought of it that way for tanks.

But I don't think rocks thats been in the tank water would cool down the tank to such an extent that it affectes the snails....could be wrong of course !

 

[thrujenseyes]

I suppose thats possible, never thought of it that way for tanks.

But I don't think rocks thats been in the tank water would cool down the tank to such an extent that it affectes the snails....could be wrong of course !

I wouldn't think so either...thought I'd throw it out there anyway on the rare occasion that someone might say "hey I've had that happen too".

 

[Flubberlump]

It hadn't occurred to me about the rocks either. The sand is really cold too because of the cold water down there, and that'll take longer to earn up than the water too

Yes I'm more concerned about the snails as the betta is swimming all over and it's more natural for him to swim around like that. The snails were spending a lot of time at the bottom, all over the rocks and the sand, now they spend most of the time on the sides of the tank and I'm worried they won't get enough to eat.

I'll go and move my heater now and go from there. I'll clean the thermometer that's in my other tank and put that in the betta tank for now so that I have two in there whilst we get it sorted. That tank is stable and I can swap it back just to check it sometimes.

 

[StevenF]

go to the craft or hardware store and by a stiff piece of closed Cell foam a little larger than your tank. It needs to be stiff so that it can support the weight (about 60lbs) of the tank without being crushed. during the next water change cycle as much water as possible without harming your fish. the goal is to reduce the weight of the water without disturbing anything in the tank. then with someones help lift the tank up and slide under it the foam pad. make sure the tank is centered on the foam and that no part of the tank is unsupported. Then slowly fill up the tank and return it to normal. That will insulate the bottom of the tank and should with the help of the heater on the bottom of the tank help keep it warm. Cut of the excess foam.

Another thing you can do is have a tight fitting lid on top of the tank to reduce water evaporation. Water evaporation cools the tank so reducing that will also help keep the tank warm.

 

[Flubberlump]

I'll see if I can find anything like that to insulate it thank you.

I've just moved the heater and put a thermometer at the bottom. The top thermometer is reading 28C and the bottom one 25C so not as drastic as I thought but I can still feel the sudden drop when I put my hand in. And it's still not warm enough for the snails down there.

I'll check it again in a bit to see whether the bottom reading goes up with the heater where it is. I hope it helps, I had to uproot most of the plants to move the heater and it's taking up most of the bottom of the tank across the back so can't plant there either Benny the betta is very interested though. He does get in the way, swimming around my hand and sticking his nose right in to what I'm doing. He's lucky he hasn't been squashed yet.

Thank you all for your input!

 

[NickAu]

Can you lower your filter intake so its near the bottom? Thats what I did with mine, I put the filter near the bottom with the outlet pointing straight up.

 

[Flubberlump]

I need to see if I can get an attachment for the outlet. It came with a spray bar but nothing else so it hasn't got anything on at the moment. I want to see if I can get an angled attachment, then I can try moving it to the bottom. I'll have a look now and see if I can get something.

 

[NickAu]

He does get in the way, swimming around my hand and sticking his nose right in to what I'm doing. He's lucky he hasn't been squashed yet.

Typical Betta just wait till you want to prune the tank using scissors then it gets real fun.

 

[Flubberlump]

Oh dear I dread to think! He's certainly nosy!

 

[NickAu]

I use one of these filters on my 2 foot tank and have no problem.