crs population decreases

guy tillmans

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Jul 29, 2008
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hello

For the last two years a had a stable population of crs's(about 30 a 40) but the last month's the population decreased until 5 species. I use presurized co2 , but my fish are fine so my shrimps also should be. The only thing i changed last months is that i use only tap water, directly in the tank when i do waterchanges. Prior to this i used half reversed osmosis and half tap.
some waterparameters:
ph 6.4, kh 3 gh 10 ammonia 0, no3 30ppm, po4 3 ppm, Fe 0.5-1.0,
What do i have to do to get them breeding again( i don't see the females carying eggs anymore).

Thanks
 

Philosophos

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IME shrimp show stress before fish when it comes to CO2. I've lost shrimp before sensitive fish, and in fact keep them in my tanks almost like a canary in a coal mine. Almost any common toxicity seems to effect shrimp before warm water fish.

It might also be stress from parameters changing rapidly. I'm not sure how it is in the Netherlands, but tap water in the US can legally contain levels of Cu that will easily achieve LC50 range for cherry shrimp (.14-.76ppm) let alone crystal red. The EPA here permits as high as 1.3ppm. Take a look over a water quality report; it should list copper levels given that it's toxic to humans as well.

The other possibility is pure adjustment shock in parameter change. I'm not sure how easy it is to do this with crystal reds, though. My experience is with amano's and cherries; neither is sensitive enough to die from anything I've put them through.

-Philosophos
 

guy tillmans

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Jul 29, 2008
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The report of the tapwater says that , our taps contains 35,7500 mg/l chloride and 2,500 mcg/l (=0.2500 ppm) of cu. Could temp changes play a role in here? For ex. cold water added during the WC (50%)?
th
 

Philosophos

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Unless you're using dechlorinator, or letting the water sit overnight, I'd say the chlorine alone could easily kill your shrimp (35ppm? I'm assumign that was actually mcg you posted).

The copper is within LC50 range for shrimp as well; 50% RO may have been keeping it below the threshold.

A rapid drop in temperature will definitely cause stress. This could have contributed, but probably didn't kill the shrimp on its own.

Personally I'd remove all 3 variables; change with water that isn't so cold, dechlorinate, and go back to 50/50 RO. You could also try running your water through carbon before making the change in order to reduce copper levels.

-Philosophos
 

guy tillmans

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Jul 29, 2008
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Thanks philo for the reply

No , it really says that the chloride = 35,7500 mg/l , i've checked ist twice, i'm sure about that. Is it enough to let 'new" water rest for one day? or should i use an oxygen pump to dechlorinize? and for howlong.
th
 

Tom Barr

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If things look abnormal with the shrimp, I'd look at the Tap.
A change in KH often will cause more problems that we often think.
Copper seems a bit high too.

Particularly for shrimplets.

Adults might be fine, but the fry often have more trouble,
Activated carbon(AC) will remove the trace metals pretty well, much cheaper than RO/easier, but you can also put the AC in the aquarium also to remove it.

Or both.

Then it's more an issue of adjusting to new KH.

3 is not bad and should pose no issues.

Regards,
Tom Barr
 

Philosophos

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What Tom said pretty much covers it. He'd know more of shrimp LC50's from direct experience than me.

Stil... that chlorine... swimming pools don't have levels that high. It must be a typo or something. Try dechlorinator until you can find out exactly how much is in the water, aeration as an absolute minimum.

-Philosophos
 

guy tillmans

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Jul 29, 2008
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Thanks folks,

I thought activated carbon permanently in your canister also has some bad influences on other processes in our tanks like the added micros and micros. Is it so?
To philo,
here are the results of my watersupplier. in the fifth row you see 35,7500 mg/l Cl.
guytillmans
 

Philosophos

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Wow guy, That's some interesting water. No need for KNO3 or MgSo4 for sure. Lots of dechlorinator sounds like a good move to me.

-Philosophos
 

guy tillmans

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Jul 29, 2008
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Hi philo

I keep my water in a tank for a few days now before i put it in the tank, is that enough to dechlorinize? Do you have other suggestions to dechlorinize? I also put in a active carbon filter in my canister ,as tom suggested, how long can i keep it in there? or change it?
 

Philosophos

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I've honestly never dealt with chlorine levels that high. A few days is likely to do it; chlorine does degas relatively quickly. An air stone would leave you with little doubt.

Just use the carbon for a day at most after the water change. You may not even need it if you age your water for a few days. I'm really not that great with calculating this sort of thing; it's one of the concepts I'm working on learning.

-Philosophos