Regular heater vs undergravel cable?

I'm redoing my 29 gallon setup. So far I've been using a regular glass-tube style heater that sticks to the back wall of the aquarium glass with a couple of suction cups. However, I've heard that plans will do much better if you use an under-gravel heating "cable". Is this really true? How many aquascapers here use the cable type of heater?

Found this one on amazon.com

I found this on on amazon.com. Looks like it would work fine in my 29gal?

[ame=http://www.amazon.com/gp/product/B0006JLPGS/ref=pd_lpo_k2_dp_sr_3?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B0006JLPH2&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0SXC2CBE8NH28HAJCR6K]Amazon.com: Hydor HYDROKABLE Cable Heater 50W 19.7 ft 16/35 gal CE: Kitchen & Dining[/ame]

By using substrate heaters, you can really mimic nature. This is with respect to the substrate and water column.

Basically as you heat the substrate, it creates convection currents all over the substrate. This is great for pulling co2 and ferts right to the top of the substrate. Ad warm water rises, this is replaced by co2 and fert laden colder water.

Next, warm substrate is good for microbial development. This allows for better life within the substrate itself and helps with the nitrogen cycle. Any detritus (fish poop) will also rot quicker when it is within a warm substrate.

I personally cannot say if the warmth improves root growth, but if the surrounding environment improves, then one would assume that the roots would develop better.

Under gravel heaters cannot replace the regular heater to maintain the tank at a certain temp, they just provide a warm flow through the substrate but will not maintain your tank temperature constant.

There are lots of arguments regarding how beneficial they are, I have never found them to be of any use, having used them in the past myself.

If you don't like the heater at the back of the tank just purchase an inline heater for your external filter, if you are using one.

I have read quite a bit about cable heaters and from the info I have gathered they are more aquarium snake oil.

Does nature have warmer soil the deeper you go? No, dig a hole and see. Its not any different in an aquatic environment.

I suggest an inline hydor heater. they are nice, efficient, and don't go in the tank.

But if you still want one I have one I never took out of the box you can have for cheap. It would work for a 29 gal. I bought it before I knew better. (good thing I'm not a salesman for a living).

How much? I live near Baltimore, Maryland.

$25 plus whatever shipping is, which shouldn't be much USPS or UPS. It is a RedSea Root therm 160. cost me some where around $60.

I will post a pic of it if you are considering.