Planted Tank Guru
Join Date: Dec 2012
Location: Hot Springs Ar. 71901
Radio Shack may have a replacement part for that. If you can solder, you could replace it.
When you intentionally do a blackout, 5 days is the minimum recommended in most cases. But you should expect the plants to do nothing for at least a week after it.
But...the good part is that this is not a true blackout...as in black plastic bag over the tank. If there is any window in the room it will be far less than a real blackout.
If you have CO2 it will not get used up as much if a partial or at all if a complete
blackout. Either could cause an issue for any fauna...fish/shrimp.
There is no book on this one so I'd think less damage in lack of a nutrient to the plants is less important than suffocating the fish/shrimp. Still your call though.
The shortest distance between any two points is a straight line...in the opposite direction...