Shane, I used cables for about 10 years total.
I had 2 clients that used them. We removed them and changed the substrate to flourite about 7 years ago.
The tanks have done enormously better and no longer require me and the clients are able to handle the tanks on their own now days.
I used 2 sets of Dupla cables, a Sandpoint Cable system, made my own cables from raw electrical parts for 5 tanks.
I live in CA, it gets hot in ther summer here, 100F etc. At least it's a dry heat
But the cables are not on for most of the spring and summer.
Any notable growth differences?
No.
I see no practical reason biologically, and we are talking about Bioloigy here, to why they would work say, any better than a Reverse flow UG filter, see the APD on my old post on those. And folks have better or at worse: similar results without the cables to begin with.
It's something very easy to test, you simply have them and turn them on/off and note any changes, differences etc in the water, the plants, fish etc.
I've never seen anything I could attribute to the cables.
I think 10 years and 8 tanks is long enough and should see something by then don't you?
George Booth finally fessed up to what the cables do in his arguement with me on the APD years ago.
He said that the effects of the cables is stablity over long time frames and that it is subtle. I argued right back: if it is subtle and provides this stability over long time frames(months or years according George) as you say, I can say that about a great many thing and it would become nearly impossible to distingush whether tank A and tank B's "subtle long term stability is due to fish load, feeding, plant biomass differences, water changes, filtration etc, or actually due to the eeffects of the cables themselves."
I think George realized he'd been duped and was using the "weasle words" to support something that really never had support. He bought into the marketing mythology from Dupla.
It works because you believe it works, not because there are anything that you can test or not easily. To date, I've never found any supporting evidence in any literature search for hydric soils that suggest this would be helpful of speed the process up any more than heating the tank itslef, or heating a filter.
The flow in/out is regulated just fine by active root growth, that pumps O2 in there for the bacteria to decompose things, and the roots remove and export lots of nutrients/waste up and into plant biomass or leach out into the water.
It's not a purly mechanical process, there is a very very significant biological component.
Another point against the cables theory: When the cables do increase the flow rate through the gravel, it'll simple exchange water through it at a faster rate. This means more mulm will get trapped in there and it'll axct more like a sand filter. That will add the mulm faster to a new tank and thus you could argue that will help the bacteria and reduce the aerobic nature of the sediement.
Or you could simply add some mulm from an established tank already and be done with it
That adds precisely what is there in a established tank and addresses that issue easily. I do suggest folks to add mulm to any new tank anyway.
Claus from Tropica has told me the optimal flow rates for sediments for aquatic plants is about 0.49 liters/m^2/day. This is regular exchange rates
without cables.
Adding more would not be optimal.
I'm been friends with Ole and Troels and they feel the same.
It's a bit of a joke within our group about such monkey business and weasle word marketing.
We know there's no support for it.
Its the ignorant (no offense to anyone here) that get taken on such marketing schemes.
And Dupla or other companies might not be willingfully misleading folks to sella product, they might believe it works.
But few companies test these products critically.
So I come along and do such test to see.
Then I see what does work vs what does not.
If something is "subtle and long term", that sends my radar up right away.
Those are weasle words.
Dupla did bring CO2 to the hobby is a big way, but hardly the first, I DIY CO2 methods going back to 1962 in a hobby magazine, CO2 did work, adding traces, while they claim they brought it, folks had been using it for years.
But the cables did not.
So they helped the evolution of the hobby, even if they got a few things wrong, now we know today and the hobby has evolved and become better and better.
So while I come off very critical at times about methods/ideas/company products, it is not out of malice for them in anyway, rather to make things better later for hobbyists.
Less guessing and more confidence in what and why things work in the hobby.
Science is ever evolving and getting better and adding to what is known.
It's not absolute. There's awlays room for doubt.
Regards,
Tom Barr