Algae Scrubber Disaster

[monocus]

my scrubber is built the same way sitting on my sump with 2" clearance to the top of my stand.i've never had any problem while or after changing.it almost sounds like your o2 is very low in your tank and when you turn the pumps off the o2 is rapidly depleted.you shouldn't be getting a spike in ammonia by changing your algae scrubber which soaks up nitrates and phosphates