Nuvo 30L Tank Crash - What Happened?

tfrechette

New member
I have a Nuvo 30L, the 36" tank.

Tank has been up for 7 months.
Added pair cardinals at 2 months
Added fire shrimp at 4 months
Added pair percula clowns at 5 months

Tank has around 20lbs live rock and sand bed.
CUC - Nassairus, nerites and hermit crabs

Here's what happened:
Thursday 3/12 - weekly 4 gallon water change check parameters - okay
Sunday afternoon 3/15 - All fish accounted for.
Sunday night -female clown not seen

Monday night - go looking for clown. I have egg crate on the top with some cutouts; found clown swimming with the pump. Must have jumped and luckily landed in the sump. Removed the pump to put her back in the tank. Noticed that the pump had some junk on the input grill on the bottom. Cleaned pump. After cleaning, noticed that the pump was shutting off and on. Removed pump again and noticed a nylon thread (from bag of sand) in bottom of impeller. Removed it, now pump blows breaker. Just run power heads overnight.

Tuesday: Go to LFS for new pump. They don't have anything suitable. Tuesday night put in my MJ1200 used for mixing saltwater in the tank.

Wednesday: order pump online Sicce 1.5.

Thursday: Leave on a trip; wife has feeding instructions and she's done this before. I have auto feeder which will drop minimum food twice a day and then feed 1/4 cube frozen mysis.

Monday Night: wife picks up at airport; bad news. Sunday morning clowns were swimming at the bottom not looking good. Monday morning found 1 dead clown and 1 dead cardinal and no one else is seen.

Tuesday: Found the other dead clown. One nassarius is on top of the sand not moving. Think he's dead but he isn't. His snorkel seems shorter than normal. Two nerites on the sand; also not normal. Check parameters; ammonia, nitrates and nitrates all zero. Kh around 7. Did water change;

Fire shrimp is still alive; two nerites on the sand bed were dead. Still see hermits moving around.

LFS points me to measuring voltage in tank. MJ1200 pump puts on 30 VAC skimmer puts out 16 VAC. New Sicce pump puts out 16 VAC. There are other threads on here about voltage and ground probes. Sounded like most people don't think that's a problem. Not sure what the AC current is in the water.

So any thoughts on what happened? The biggest change was the pump. Going from the 450 gph Nuvo stock pump to the MJ1200 rated 250. (Power heads were running.)
 
Through all this, did you check water parameters at all? Or your wife anyways?

I think it may be that when you took the pump out, you'd have stirred up detritus or something and polluted the tank but... not sure at all. Because generally that's not the issue. But powerheads should have definitely been fine overnight... and you have no abnormal stray voltage. Weird.
 
I'm thinking residue from cleaning the pump or the Maxi had something on it. Gotta be something like that to affect so much so fast.
 
What did you use to clean the pump the first time?

Mechanically cleaned the pump on Monday night with brush I use to clean skimmer. Bottom grill of pump pops off so easy to clean. However, after cleaning; the pump popped the circuit breaker so I removed the pump. Ran the tank for 48 hours with just one MP10 power head probably running at 50%.

Wednesday night put in MJ1200 as return pump. Following Monday morning fish are dead. One think I realized was that MJ1200 was installed in Apex output 1 which is semiconductor switch. So during feed cycles it did not completely turn off.

Thanks for any suggestions.
 
This is really strange. Did your wife do any cleaning, where something could have got overspray into the tank? Your water tests were good, you still had good circulation, can't see where a pump going down would hurt your system. Can't see a 02 problem with a mp10 running.
 
Definitely sounds like something got into the tank over the weekend. No carpets cleaned, etc. while you were out of town?
 
So at what point would you add livestock to the tank? I'll do a 10 gallon water change. this week. But not sure what I'm getting rid of.
 
Run charcoal for a while and change it out several times. Then add some inverts then throw in a damsel or something. Whatever it is may have killed off the nitrifying bacteria as well so you may end up cycling again. You don't mention if you have any corals - if so, how did they fare? Usually, they're much more fragile than the fish and inverts.
 
Obviously it's been a long day and I have my BBQing pork loin on the mind - carbon, not charcoal.
 
My guess was toxins as well. Poly filter works good for removing toxins as well When I worked at a fish store I had a "fish sitting wife" come in describing similar meltdown and loosing half the fish and corals looking weird since the morning. Checked water parameters, temp etc. then stumbled across the fact that she had cleaned the inside of tank with a scrubbing pad and only used "a little" bit of detergent. She put in a poly filter and did not loose anything else.
 
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