DIY SUBSTRATE HEATING NOT USING CABLE

[paulj]

I am converting a 4' x 18" x 20"marine tank to a planted tank and was reading the AquaGreen article about using pipes to conduct warm water throught the substate and my aquarium uses a sump where the water is pumped back into the tank trough a hole in the base of the tank. I had an idea about using irrigation poly pipe to divert the water from the sump trougn a 12mm manifold on both sides of the tank and 6mm connection pipes to heat the substrate and returning the water to the tank by a spray bar. The back siphoning to the sump is stopped by a irrigation non return valve (with the spring removed) on the return pipe from the aquarium. I have using the non return valve for about a year on the marine tank and it works well. Has any one tried this before? Any comments or suggestions would be appreciated before I try it. Thanks in advance.

[ILLUSN]

Sounds like a great idea! will 12mm manifold be wide enough for the flow from your pump? you might need to put some kind of flow contol valve (ball valve) just before the spray bar so as to keep enough water flowing through the system of 6mm pipe to heat the substrate.

[paulj]

I am using a 3000L return pump with a head of only 900mm and I may need to increase the manifold to 19mm poly pipe instead of using the 12mm but still using 6mm cross pipes. I am still deciding whether to run the mainfold length wise or cross wise in the tank have not done the hydraulics on CAD yet, any advice? I have a spare 2' tanks and I will experiment with it first. I can not strip down my small 4' tank until I find a home for 2 x 700mm epaultte sharks in my 4'x2'x2' tank. Thanks for the reply.

[ILLUSN]

cross wise would be cheeper, lengthwise will broably give better results, 19mm will flow alot more then 12 but with 6mm cross pipe, you'll have major restriction points, the fater will proably try to flow around the system (streight from the manifold to the spray bar) rather then through it, but you wont know till you try. 3000lph with ony 900mm height is going to flow pretty quick (whats the hmax of the pump? 2.5-3.5m?).

[paulj]

I have not even started yet and the design has changed already, two brains are definitely better than one, the latest design seen to be 19mm lengthwise and 12mm crossflow and return the water by multiple open returns rather than a spray or having a longer spray bar with larger holes. The pump has a maximum head of 3m, I am currently using it for a marine tank with a rotating head return. Another question if is not impolite will the use of a plenum under the substrate help the flow through the gravel? Thanks

[ILLUSN]

multiple jets would aid in water flow around your aquarium and make it easier for your filter to remove more cr@p (no dead spots of poor circulation).

if you make your spray bar holes too wide all the water will rush out of the first few only, again you wont know till you try, i assume any project like this is going to take some trial and error, but it will be very cool once done.

as for water flow through your gravel, if you've got warmer water in the gravel then i the water column, convection will cause the water to rise through the spaces between the gravel, as it does cooler water will return to replace it. this is the principle behind substrate hjeating. I've been using heating coils now for 4 months and there has been no anerobic spots (yet) in my 6 inch substrate bed, so i assume water is flowing through it nicely.

[paulj]

Thanks for the information. The only way to see if it works is to draw it up and build it. The other question I had is whether the addition of a plenum under the substate and heater is of any advantage? Thanks

[ILLUSN]

if your water is warm enough i dont think you'll need any intank heaters, but your sump might have to run 3-4degrees warmer then your tank to get the right temp in the water column.

[paulj]

Thanks