Sorry I missed this thread.
I began using natural river sand and aquarium gravel in the first tank I cycled, that was May 2008. I use real plants since day 1 of fishless cycle in all my tanks, except if delicate species.
Upgrading my inert substrate with Eco-Complete (and other alike substrates) have been one of the major boosts I have experienced in planted tanks, side by side with improved lighting and CO2 injection.
There are different ways to work with it.
My first experience was tearing down a whole tank (29gal bow tall, footprint of 20gal long), placing fish and plants in a bucket, as I removed most inert aquarium gravel and left some natural river sand which I mixed with recently collected sand in another bucket.
I placed barely 10 lbs of Eco-Complete in the bottom of the empty tank, making a thicker layer towards the rear wall of the aquarium. I added the natural river sand on top, ending with a 1:3 mixture (one part Eco-Complete as bottom substrate; three parts of sand as top substrate). This meant my first successful attempt at keeping Sword plants (although they barely made it until I improved lighting). It took me like one hour to perform this.
My second experience with Eco-Complete meant tearing down another tank (40gal long), placing all fishies in a bucket, removing all plants and as much sand as I could (almost negligible amounts of sand remained here and there). I still keep this tank with Eco-Complete as the sole substrate (I "refurbished" it almost one year after set-up as I introduced 30lbs more on top of the first one in a major upgrade). This time it took me almost two hours.
Eco-Complete is a rare to find product in Santo Domingo. I have it in almost all my tanks (exception made of the Hospital/Quarantine
bare bottom tanks, the river sand only
FW White Crayfish tank, and of course my Nano
SW). I mostly use mixture of natural river sand with these type of substrate. I also tried and like the quality of Activ-Flora (Floracor Black). I ordered three 12lbs bags of Azoo Plant Grower Bed (those are coming by sea) but haven't tried it yet.
Thing is: It's up to you to either replace the whole substrate, mix some of it with existing substrate, or mix with new gravel or sand. Some fishkeepers with light-to-moderately planted tanks use a bunch of enriched substrate at the spots where they expect to place their rooted plants.
It is possible that transient elevations in
pH and KH occur in a tank fully upgraded from inert substrate to Eco-Complete (or alikes). Although it doesn't necessarily happens each time. One of my tanks took almost 4 weeks to go back to where I wanted it; most of my other tanks, the change was quite insignificant.
Pepetj
Santo Domingo