Cleaner for large grain sand bed??

[Cassian]

Hello all! I have a 180 gallon aquarium with volcanic black sand. The sand grains are fairly large and my sandbed is covered in algae. I was going to get a diamond watchman, but I’m worried about it injuring it’s gills with the large grains. Would a conch be a better choice? How many of you use conches and do they keep your sand clean? (Any pics?) how many conches would be suitable for my 180 (8 foot long by 2 foot wide with about 3 in sand bed.

Are there any better options for me ?

 

[reef lover]

Def go for conchs!! Probably 5 to 6 for that size tank.