substrate heating - total failure

[justDIY]

alright, a few months back I setup a 10 gallon tank with a diy'd substrate heater, and about 3" of a gravel / profile substrate.

the heater was approximately 40 watts, and consisted of a tin/copper wire (with teflon insulation) wound around a pvc frame, placed in the very bottom of the substrate.

plants consisted of a mixture of stem and rhizome plants, several species.

anyway, all the plants are now dead and gone

now I admit, this tank did not recieve my undivded attention, but it got water changes and gravel vacs on occasion. fish load is 5-6 platies and some oto's

filtration is a pengiun mini running without any cartrdige

lighting is a 20 watt GE plant and aq bulb and a 15 watt GE daylight bulb

I will post some before and after pictures for your horror

anyway, substrate heating gets a big red X in my book.

 

[brendan]

Sorry to hear about the substrate heating disaster. A DIY project like that is sometimes risky in terms of whether or not success will be achieved. Searching the Internet I came across a page where someone has attempted substrate heating as well however it appears that they used a commercially bought product. I've searched around my lfs but haven't been able to find the same type of heating coil, who knows maybe it's also a diy. It looked interesting though, thought it might give you some ideas if you try again.

Here's the link
http://members.shaw.ca/dclubine/master.htm

 

[justDIY]

well, the project was started in my stone-age era of photography (pre digital)

so, here's a crummy "before" shot, the tank had been running about a month

and here it is now

the sword plant is just being stored in that tank till I find room for it elsewhere.... the only plant still alive is the anacharis, which seems to be doing well.

 

[William]

Is that anerobic patches in your substrate?

 

[justDIY]

I don't think so - it looks (up close) to just be green algae growing on the glass, down where the snails and algae eaters cant get it

what is odd is how there is no algae growing in a "bowl" shape for the part of the glass the sword's clay pot is by... wonder if that sword is sucking nutriants from the substrate through a clay pot!

the front of this tank gets about 2-3 hours of intense sunlight each morning, which I think is the cause of all the algae.

 

[BBReef]

Do you have any kind of CO2 injection in that tank. In my oppinion 3.5 watts per gal is a lot without any kind of CO2 injection and could also be a big part of the problem. Just a thought.

 

[justDIY]

I ran yeast co2 into the filter until everything died, then I stopped... tank has been like that for about a month now, just too busy to tear it down

 

[justDIY]

OK I tore it down last night, and was feeling around in the gravel for any root balls or bulbs that may be still viable (found one!)

anyway

the gravel was in excellent condition - no bad smell AT ALL, no black patches of goo ... so ... I was hoping that william's idea about anaerobic might be right, but no dice

it was a bit weird, because the gravel was warm, and you usually expect it to be cold ... but it's not like it was HOT or anything that a tropical plant could not handle.

I'm still at a loss at to what caused the failure..

 

[madasafish]

IMO, a heater located under the substrate (I've thought about it before) might not sufficiently heat the tank... I could be wrong... But a lot of the power of a heater comes from the fact that it can warm water that is in motion. When water is warmed in patches of generally unmoving water trapped in the substrate this could potentially cause stress on the fish and a wierd thermodynamic *dynamic* in the tank.

Of course, the warmer water would theoretically rise... but possibly quite slowly. Was the heater temperature-activated? Did it turn on/off when the tank reached a certain temp? I've found my plants to be extremely sensitive to water temp change, esp. when the water gets colder than usual....

Just a thought. It could be quite wrong.

P.S. Why a penguin mini w/o filter pad? What was your chemical/mechanical filtration method, or were you relying on the plants and substrate to do all that?

 

[brotherd]

Interesting thread!I had read a book about planted tanks(an older book)And I've even seen ads for substrate heaters.The only reason I never tried it was that I could not source them locally.My current planted tank is doing very well with a submersible heater,150 gph hob filter,and about 3 watts per gal. lighting.I also do 25% water changes weekly and add a liquid plant grow from Hagen.Oh ya I also have the DIY co2 set up.The substrate is laterite.Anyone else have any experience with substrate heaters?

 

[justDIY]

well, the water stayed a pretty constant 75-77 degrees, except for when my apt heat was malfunctioning... the heater was on a timer, it would cycle on for 15 min intervals and off for 30 min intervals

the water was heated through conduction and convection, same as a normal tube-shaped heater works, although in this case, having the substrate warmed acts as a "thermal mass".

the whole idea of substrate heating is to cause a thermodynamic convection in the water, drawing fresh oxygenated water into the substrate and expelling depleted water. I can say that this works, and works well - the immaculate condition of the substrate was testimant to that.

perhaps the convection was too strong, and did not allow the roots time enough to absorb nutriants?

if I end up with a home one of these days, I'll try it again - for now, I need the space for other projects

 

[madasafish]

Yeah, I thought that convection might the justification for the substrate heater idea... When I thought about thermod-s in your tank, that certainly came to mind. Sorry I can't help. I'm really fairly new to the planted tank. I think I'll have more experience after setting up my 55 planted!

P.S. Happy belated birthday (I think I remember it was the 2nd)! I'm a day before you. You share your b'day with Monica Seles, btw.

 

[Doraemon]

I think 40W may be too much for 10g. A 50W was recommended for my 70g tank. (I bought the heater. Didn't feel confident about making it myself) If the gravel is warm to touch, I would guess that it is 80+ degrees. Would that be too much for the plants. Maybe the sword is doing well because it has the pot to reduce the heat.

Just some thoughts and observations.

 

[Guest]

Yes, I also have experience with them. Substrate heating coils, essentially a long wire run back and forth along the whole tank bottom, under all substrate. I had my 90 gallon set up with sub heat for 8-9 months. Then, I decided to do a major re-arrange. Bloody disaster! my swords and Crypts had grown roots all throught the coils, and it all came up whn I pulled the plants. Long story short, I didtched the substrate heating, and my tank is doing just as well as it did with the sub. heating. So, my exp. (others certainly may differ), it's worthless. quality substrate is the key, IMO, and regular tank heating is fine.

 

[itafx]

Without sufficient water motion, you get a thermocline - a layer of warm water and another layer that is much cooler. I've had it happen in my tanks that have stealth heaters suction cupped to the side. I would think that relying solely on a buried heater would be even more apt to result in a thermocline. However, I am interested in the idea of substrate heaters for the benefit of the plant roots. I read somewhere that it isn't helpful and I haven't tried it yet, but I'm still thinking about it. I've reached down into the substrate in my warm tanks and found the substrate to be quite chilly under the surface, especially in winter. You can get heat mats for propagating plants in a green house. I have one that is thermostatically controlled. I wonder if that would work...