Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Yes, you can. There are 2 basic ways, and I suppose endless variations.
1) Replace it all at one time. Remove fish, plants, decor and water, scoop out gravel, pour in the EC, rescape, refill, put the fish back. Some chance of a mini cycle, but the plants may make the difference, just watch the NH3/NH4 and NO2 and do water changes as needed. Fish can live in a bucket or two during this swap. Especially good if you have a small air bubbler. If the house is cool then wrap the bucket to keep it warm. The nitrifying bacteria in the filter media are fine for an hour or so with no water circulation. They need humidity and oxygen, and do not actually have to be under water.
2) Replace it in sections. This might mean removing 1/4 of the gravel, then pouring the EC into the tank through a tube (not just through the water). Then a week or two later another 1/4 of the tank. Least chance of even a minicycle. More disruption over a longer period of time, though.
Variation of 2): Pour in the EC on top of the gravel, (through a tube) in sections, and let it sift its way deeper into the gravel. Remove as much of the gravel as you want, over time. You will never get rid of it all, but that is OK.
Do not rinse EC, use it straight from the bag. I understand Flourite requires a lot of rinsing, and would not be possible in -10 conditions.
Something close to 2 wpg can be high light, especially from T-5HO bulbs. Lift the bulbs higher away from the tank. 48/29 = 1.6wpg, and from T-5HO this is high enough to require Excel if not CO2, and regular fertilizing.