Fed Up of the Battle - Shrimp Death Mystery

[~firefly~]

Well, after a month battling black beard algae and unexplained shrimp deaths (now lost about 8 in a month...all cherry shrimp), I think I need to start again with my 30 litre nano shrimp tank. Tonight I found another two dead shrimp. I've tested my water:
Ammonia = 0
Nitrite = 0
Nitrate = ~5
pH = 7.0

Usual routine is 30-40% water change per week, including swilling the filter (in removed tank water). Daily drops of fertiliser and EasyCarbo.

I just don't get why I'm losing shrimp suddenly (and so regularly...it's at least one a week at the moment).

There are a few things that might be responsible, here are my observations:

Reason 1:
Black Beard Algae - had a small outbreak whilst I was on holiday in January (caused by, I think, halved dose of EasyCarbo and ferts as a friend was looking after it for me, visiting every other day). Outbreak was slight (only visible on a few blades of grass and on a little bit of the moss - probably wouldn't cover an area larger than your little fingernail). Anyone know if BBA is toxic to shrimp? I've been picking it off where I can and trimming it out of the grass, but the grass doesn't seem to be catching up and despite resuming normal dosing, looks very poor.

Reason 2:
Change in fertiliser. Might be a coincidence but I switched the ferts I use (as I ran out of the one I had). However, I am using fertiliser that is shrimp safe (both as reviewed online and as used by my LFS in their shrimp tanks). I dose at less than 25% recommended dosage in a water change and split daily doses (again at less than 25% dosage rate) over several days rather than dumping it in all at once. I'm reluctant to stop the fertiliser as I would like the plants to get ahead with this.

Reason 3:
Toxin build up in my "moss tree" - I'd started to notice that over the past month or two the tank was looking grubbier and grubbier. Debris and browning plants. Just lots of bits floating around, lots of waste. It all seemed to accumulate in the moss. I frequently gave it a little blast with a pipette - gently blowing water through it to clear the debris before water changes.

Reason 4:
Freshwater limpets - a problem in this tank. Not sure if they could ever cause problems for shrimp?

Reason 5:
Disease? No symptoms in the shrimp - other than they won't breed. I had 10 rili shrimp and 15 cherry shrimp. What is strange is the ONLY deaths have been in the cherry shrimp population. About 4 months ago one shrimp had eggs, then I never saw it again. I'm pretty sure I have a mix of males and females.

Coincidence No. #967:
Plant growth had slowed dramatically - moss looked brownish and very slow growth. Poor. 3 months ago I was having to trim it every week, now it barely grows. Not sure why. Grass also poor. Maybe me going on holiday upset the balance of everything?

I got so fed up with the situation tonight that I pulled out all the moss on the "moss tree". The moss wasn't growing well lately anyway. The tank is now a bit bare - and better lit, but I just want to try to keep it as clean as possible for a while to rule out the "mucky moss" theory.

Unless I'm advised otherwise on here I'm going to do 30% daily water changes for the next week or two, before reintroducing some new/clean moss from my fish tank.

Odd? Strange? Any suggestions greatly appreciated. Feel free to ask more questions as I'm stumped by this one. I currently have all the moss I pulled out sitting in a bucket of water. I'll pick through it later this evening to salvage the greener parts.

[~firefly~]

Also, I can post photos of anything in the tank if required for a diagnosis.

[talldutchie]

1st things 1st. What's the temp?

[~firefly~]

24C

Too low?

[~firefly~]

Here's a photo of the ugly thing without the canopy now. (whether you want photos or not!)



Detail...oddly, the rili shrimp seem to have scarpered after today's change. Perhaps more sensitive to light.





It's odd that the grass and moss stopped growing as the Alternanthera is doing well.

[~firefly~]

Any suggestions?

[madagascariensis]

regardless of manufacturer's recommendations, daily dosing seems to me like a lot, and especially when your plants are stagnating and not using up the fertilizer, it might cause a gradual build up?
while the fertilizer might be labeled shrimp safe that probably applies only for regular dosage, as in the end, everything is harmful in too large quantities.
sounds far fetched but as you must have already noticed, there seems to be no obvious answer to the problem.

[Loller]

It could have to do with hardness... I had a shrimp death event but fixed it by raising hardness. Though it is odd that your rii shrimp are doing better. If you recently added a new shrimp, it could of brought along diseases.

By the way, LOVE the tank. If you want to see mine, I can post it.

[~firefly~]

I calculate weekly dosage. Dose the water change volume at 25% strength, then split the remainder over the days of the week. Does that make sense? Total strength shouldn't get above that really. I'm not dosing the full calculation daily.

I'll do the daily water changes as planned for a week or two.

[~firefly~]

Hi Loller,

With London water...I don't need to raise the hardness, believe me. The shrimp I have were bred in London water so that shouldn't be the issue. I don't have a test kit for hardness though.