Originally Posted by eileen
Byron, I was going to get the Excel and get rid of my big 16.9 fl. oz bottle of Florish Comrehensive as I noticed when I used it the algae got worse on my tanks glass. You said that this stuff if the best but how much of it should I be using? I have a two 3 gal, 6 gal, 10 gal, 20 gal, 30 gal. size tanks.The directions say 1 cap for every 60 gal, so my 30 gal. would be 1/2 cap not sure about the small ones maybe 1/8 tsp. It says once or twice a week. Should I use it when doing my weekly water changes or once a month. I'm just not sure and was going to craigslist it or take to my fish club auction. I have 1 15 watt bulb and all low light plants and on a timer for 7 hrs a day for light. I also do a 20-25% water change at the end of each week.
Eileen, Excel is simply carbon, nothing more (in terms of nutrients), so it is not a general or comprehensive/complete fertilizer. As you undoubtedly know from my many posts, plants require some 17 nutrients, of which carbon is only one, albeit a macro-nutrient. Unless all 17 are available, plants can't utilize more carbon, or more light, etc. That balance again.
There is a lot more carbon from CO2 in most aquaria than many realize; fish obviously produce it during respiration, but so do plants--and so does bacteria, and there is more CO2 from bacteria than the fish and plants combined. Provided the other nutrients are also present, and the light is adequate (in intensity, spectrum and duration), the plants will be thriving. Slower growth, yes, but I see nothing wrong with that if it means dumping less stuff into the fish's environment.
I use Flourish Comprehensive twice weekly, and I pretty much have to or my swords begin to yellow. I set up my 70g two weeks ago with Flourite substrate, the first time I have used an enriched substrate; it will be interesting to see if the swords (this tank is my flooded Amazon forest, full of Echinodorus species) do better and also if I can go down to once weekly. Anyway, they recommend what amounts to 2.5 ml or 1/2 teaspoon Flourish for each 30 gallons; I use a plastic 1/2 tsp measuring spoon. In my 33g I use a full spoonful per dose. For my 10g I use almost a full spoonful. For your smaller tanks, I would use a 1/4 teaspoon and not worry about it. Probably once a week will suffice; you have to observe the plants' response and if yellowing leaves appear go to twice weekly.
Definitely use it weekly; it is not going to last a month, unless perhaps overdosed, but that could cause other problems. And a day after the water change, as conditioners that detoxify heavy metals will negate the micro-nutrients that are heavy metals (iron, zinc, nickel, manganese, copper) if used consecutively, according to Seachem.