A week ago I moved one of my Drops from the big fish tank to my small Dwarf Gourami tank (10 gallon tank with about 8 1/2 gallons of water). I did this because I am getting a bit frustrated trying to get the nitrates down in that tank by water changes. I've been changing 4 gallons of water daily (2 in the morning and 2 in the evening) for a couple of months and nitrates stubbornly remain between 10-20ppm. Yesterday I did full tank cleaning/maintenance, changed about 75% of the water, pulled the canister filter offline and added my second Drop. Starting water params were:
Nov 07:
1. pH: 7.0
2. Ammonia (NH3): 0.0
3. Nitrite (NO2): 0.0
4. Nitrate (NO3): 3.0
5. Phosphate (PO4): 0.25
This morning (about 18 hours after the above tests) nitrates are 2.0 (excellent!) and pH, ammonia and nitrite the same. I did not test for phosphate but will at the end of the week.
So now, the only filtration on that tank are the two Drops. I'm going to test daily for the next week. I expect nitrates to stay low or maybe go to zero because the canister nitrate generator is gone. My concern now is that ammonia/ammonium also stay at zero. I have a male and female Dwarf Gourami and a couple of big apple snails in the tank. Feeding is pretty light.
If the Drops can keep the water at or near pristine, I will swap tanks with my Dwarf African Frogs, who are currently in a 15 gallon tank. The 10 gallon tank is adequate for the frogs and the larger tank will enable me to get a second pair of Gouramis. You may wonder why. The short answer is I've lost nearly half a dozen Dwarf Gouramis to nitrate poisoning. These guys need pristine water and are very sensitive to any nitrate. You may wonder why bother. These little guys are very beautiful and friendly.
I will definitely report how well the Drops maintain water quality as the sole filtration in this tank.