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50% weekly water change is killing my shrimp?

Neil6

Member
Joined
12 Dec 2020
Messages
47
Location
Uk
EI fertilizering for a 200lr heavily planted tank. Rules state do at least a 50%water change weekly but each time I do this I kill a few more 🦐 shrimp. Mostly cherry shrimps but today a few Amano too. Temperature of the water is good and it's RO water so no problems with chorine/ copper.
By the end of the week the TDS is heigh 300-400 hence the RO water being used to bring it down. Is the shock difference of the TDS killing off my shrimps?
Most shrimp keepers say don't do 50% water change so what do I do?
 
Is the RO remineralised? If its straight RO then the tank is likely low on minerals essential to shrimp.
If your tds climbs so much it cant be controlled by normal weekly water changes then you need to reduce your fert dosing as the plants arent using enough .👍
 
That makes sense. So I need to slowly reduce my ferts till my TDS balances out over the whole week? Around the 150? TDS does reduce with the water changes but climbs again over the week. Using the recommendation for EI fertilizer- plants not growing enough yet?
Shrimp die almost within an hour after water changes. Can the lack of minerals in the RO water do this. I suppose the difference between the two does it? 🧐
 
That makes sense. So I need to slowly reduce my ferts till my TDS balances out over the whole week? Around the 150? TDS does reduce with the water changes but climbs again over the week. Using the recommendation for EI fertilizer- plants not growing enough yet?
Shrimp die almost within an hour after water changes. Can the lack of minerals in the RO water do this. I suppose the difference between the two does it? 🧐
After water change TDS is '101'
 
Keep in mind that your Neocaridina (Cherry) shrimp will want a certain amount of GH in the water, I see many others have found around 6 degrees GH to be a pretty good spot. So you dont want your TDS to be too low either. But given that amanos have died right after waterchange, im leaning more towards shock. Amanos are quite hard to kill
 
Tds climb is normal but if you base is 150, if you add say 500 tds (arbitrary) of ferts over the week it should still remain below 200 by the end of the week. 1 rest day and 50% wc should then reset it to your base at 150...
It's not always that simple though, my shrimp tank for example bases at 180 and I have to WC at 100 to maintain that as pollution is pretty high and I dose a lot of mineral feeds over the week.
Ultimately if your tds rises lots during the week as you dose start pulling your ferts back a bit as the plants just arent using it or give it a mid week rest day etc...
 
Also as shrimp die quickly after WC, is the RO water your own? Some shop have terrible R0 tds 80 etc which firstly is a waste of money but will also likely need dosing with something like seachem prime...
 
If you are doing water changes with pure RO, you shouldn't be seeing TDS anywhere near 400-500, even from very generous fert levels. What is the TDS of your RO water?

It might be worth posting a full tank shot also, but do you have any sources of Calcium Carbonate such as Seiryu stone in the tank?
 
i've only tried to keep amanos once so far and they lasted around 3 months before all 4 had passed, have kept cherries for a few years now and have done fine with 70% water changes 1-2 times a week but i also do occasionally see a couple which appear to be 'dead' during or after water change, i've also went back to remove them say an hour later and they are up and grazing again

As @Wookii mentions there is something not quite right if your TDS is rising to those levels in a week, there is something that is being added well in excess (ferts or.....?) or something leaching from within (such as calcium from rocks or tannins from wood). i'm lucky to have extremely good tap water around 40ppm TDS and reset to around 120 TDS after a w/c with it raising to around 180 in a week of EI dosing (currently it rises to around 220 due to very low plant mass as i'm waiting on plants like others so there is excess nutrients not being used)

If the shrimp are new to you then yes you will no doubt get a few casualties as they adapt to your water and regime, but once you have had them breed a couple of times they soon become bullet proof to most setups. consistency is key for ideal scenarios but keeping tds within a range of 100 is more than acceptable for most inhabitants
 
I find amanos pretty much indestructible, I have had a situation where have had to move a few amanos from 120 TDS water to a tank with 380+ TDS without acclimatisation and they have been fine. Of course not recommended.

You don't mention what hardscape you have, in a rock dominated tank TDS can rise quite a lot due to the rock leaching minerals.
 
How are you changing the water? If it’s added too fast then the change in parameters could shock and kill the shrimp, also temp? I keep shrimp and when I change there water (60l tank) I drip the water back in so there isn’t any sudden changes.
 
Recording and keeping an eye on the TDS levels daily. Already reduced the micro and macro's slightly so see what that does.
 
Recording and keeping an eye on the TDS levels daily. Already reduced the micro and macro's slightly so see what that does.
So I've been monitoring the TDS over a few days
Monday=134
Tuesday=146
Wednesday= 158
Thursday= 168
Friday= 179
It's climbing a lots less than was beforehand.
Do I knock back the macro / micro ferts a little more? What is the optimal TDS for the plants /shrimp? Do I need a 50%weekly water change tomorrow?
 
So I've been monitoring the TDS over a few days
Monday=134
Tuesday=146
Wednesday= 158
Thursday= 168
Friday= 179
It's climbing a lots less than was beforehand.
Do I knock back the macro / micro ferts a little more? What is the optimal TDS for the plants /shrimp? Do I need a 50%weekly water change tomorrow?
Cherry shrimp are fine at those numbers, most would say 200-250tds for cherries but I know many on here keep them in tanks with full EI dosing and lots of rock so there TDS would be very high.

It's more the sudden change in TDS and other water parameters that can cause harm.

I remineralise my RO water to around 120 TDS in my planted tanks and 180 in my dedicated cherry tanks
 
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