how long on deli shrimp ?

So I read the beginners sticky that to cycle the tank, add live rock and a deli shrimp. We have 1 lb of rock per gallon, now we are tossing in the shrimp. Is the shrimp supposed to be in for 5 minutes, 5 hours, 5 days, or 5 months ?

 

Until it is no longer there. The point of the shrimp is to decay and produce waste for bacteria to eat and reproduce. This is called the cycle. It normally takes about 30 days, but can take longer.

 

Also there is some brown slimy stuff forming on one of the plastic plants, is that algae ?

 

Likely diatoms. They feed on silicates released from new plastic. They're kinda like algae.

 

are they bad ?

 

They come and go. Usually about 2 weeks. Then if you add a new pump, powerhead, heater, or anything else plastic, you'll get them again for a little bit, then they disappear.

They're heavily limited by the silicates in the tank. It's also not like nitrate or phosphate, which is just released and decomposed when regular algae die so new algae can use it; silicates stay bound, so new diatoms can't use it.