foxfish said:
Heating cables & mats were most definitely promoted as an aid for planted tanks.
The idea was the cable created a very slow circulation current within the substrate drawing down nutrients & the mats simply kept the roots warm.
I can also remember a heating tube that actually ran tank water via a powerhead through an 3/8 tube placed under the substrate.
I guesse things just come & go in fads, I still use heating mats under two immersed set ups.
I used Reverse flow UG filters made from PVC pipe, actually CPVC which is smaller yet, this did fine, but I turned them off, the plants still did fine, also did the same with Heat cables to illustrate the lack of any benefit.
Simple test to solve the issue.
Seedlings need optimal temps to germinate and since terrarium and terrestrial plants cannot use an aquarium water heater........since.........they in fact lack water......this same claim was aplied very incorrectly to aquatic plants, but we raise cuttings, not seedlings and we already use heaters.
Once plants are in the soil, sand etc...they pump massive amounts of O2 to the root zone rhizosphere.
Cross sections of aquatic plants are pipes used to pipe O2 down there. The plants themselves influence circulation, we/they do not need any extra help.
You can also use a Redox probes to measure slow circulation at various sediment depths and use this as a measure of optimal sediment conditions.
If you want to measure flow rates, another tool would be using Rhodamine dye and a spectrophotometer and take syringe samples out at different locations/depths over time.
There's 4-5 ways to answer the question, the most obvious is simply turn off the cables and see what happens.
We have little choice if it gets hot, so most of the summer, the cables were shut off. Plants grow faster at higher temps, so temp must be watched and accounted for.
MANY DID THIS AND SAW NO DIFFERENCE IN PLANT GROWTH/HEALTH.
Next back peddling step that cable proponents went with was it provides "long term stability" to planted tanks, well, so does a larger filter, so does an aquarist who is not as lazy and is willing to take better care of the tank, so is a good CO2 system, etc.........many things provide long term stability. A lack of stability is not caused by a lack of heater cables in any case I've ever seen. The most stable bullet proof tanks I've had used soil or plain sand......nothing else. 7-10 years without issues.
The 180 Gal planted tank uses ADA AS alone, nothing else and it's doing as good as ever.
No algae issues, it's had problems here or there,and changes.......... but nothing related to sediment. I would be lying and dishonest if I said I think there is something to heater cables, I've looked, and spent a lot of time on them and have methods to test and measure them.
Seedling trays, terrariums? Sure, you cannot use stick heaters since there is no water column
