I have tried HC on eco-complete and have failed twice miserably. If you have any fish that might even swim near the bottom (my ottos and cardinals were to blame) it becomes uprooter very easily as eco-complete is fairly uneven size substrate that I feel is actually rather large. Heres I write up I just did on another thread in this category. I personally won't try HC till I grab a few more bags of Activ-Flora and take out all my eco complete in the tank I want to use. I'm not saying you won't have success but I never have with eco-complete.
Heres the post:
Don't think this was mention but Activ-Flora, my favorite substrate hands down. Runs around $25-30 a 16lb bag. This is a very fine substrate thats about sand size. It's fairly heavy too so gravel vac-ing it is a breeze. Not to mention since it's dense, small size you can plant anything extremely easily and stay. I have this in a 10g Tetra Kit set-up with only 1 stock bulb no co2 and no dosing and plants grow better in there than my 29gal with 2 T5 HO's planted bulbs, 1 T8 10k, Eco-Complete, root tabs, dosing, and co2. I refuse to use anything else on any of my show planted tanks after my experience with this stuff. Here's some stuff I pulled off there site:
Elemental Analysis
Aluminum ..................10210
Magnesium .............. 2281
Barium ..........................124
Manganese .....................64
Calcium..........................195
Sodium.........................223
Cobalt...............................6
Nickel............................12
Chromium........................13
Vanadium.......................15
Copper ............................17
Zinc...............................29
Iron.............................18500
Potassium .................. 2195
Units=mg/kg
• Bio-activ Nutrients™ for faster, healthier plant growth.
• Contains LIVE® Heterotrophic bacteria for Instant Cycling® of your planted aquarium.
• 100% Natural - does not contain artificial dyes or additives.
• Promotes healthy root system - Activ-Flora™ is extremely microporous
• Will not alter pH in your Planted Aquarium.
• Natural bi-segmentation™ process to promote optimal Oxygenation
• Naturally Spherical grains promotes maximum diffusion (aeration)
• Activ-Flora™ is rich in Iron, no need for laterite.
http://www.activflora.com/
*Note* My 12 Long in my signature has this in it and I started that gloss carpet from 1 single pot of glosso for the entire tank 6 months ago. Mind you I only used co2 every other day or so and never did root tabs till two months ago. Not to mention I only have HE T5's rather than HO T5's so I highly recommend this stuff