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Discussion Starter · #1 ·
I did a large water change the other day, ~60% and noticed both RCS and Amanos went into hiding afterwards. I don't see any dead ones, ammonia spike, or empty shells. I still see some hanging around and eating and they seem to be increasingly back in view now two days later. I'm making other changes in the tank, such as recently added a few more of each shrimp and still dialing in CO2 and light. So their behavior may not be related to the water but I want to get some water change "best practice" from people who raise them in a mixed tank and understand what TDS changes are critical or concerning.

Generally, in addition to a weekly ~50% change, I do 2-3 small (5-7%) informal changes during the week as I trim and clean. I'm using water straight out of the tap, 2x Primed in a bucket first. It's not really an option for me to let water sit out for days or I'd probably do that.

Reading about RCS sensitivity (and assuming Amanos are similar), it sounds like a 50% change might be too much for them, particularly with a large TDS shift.

At the last water change (~60%), when they went into hiding, my parameters changed from:

Before change:
pH 7.0
dkH 6
dgH 14
TDS ~ 340

After change
pH 7.1
dkH 5
dgH 12
TDS ~ 260

Is that enough of a change in parameters to cause a problem or behavioral change with shrimp?

Other tank stats:
50 gallon, CO2 injected to ~ 20ppm during lights on
Heavily planted > 90% and dense
~ 40 endlers (many of which are fry or juvvies)
~ 100 RCS (if most purchased are still alive, gradually added over last 2 months)
~ 14 Amanos (if most purchased are still alive)

I am thinking I should maybe break the water changes into 3-4 20% changes per week to be more gentle on them.
 

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snails are your friend
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I am thinking I should maybe break the water changes into 3-4 20% changes per week to be more gentle on them.

I think this would be prudent, but if not overfeeding seems more than you should need to do. I was doing 50% weekly on my Osaka cubes but had occasional WRoD issues. Not on a large number of shrimp, but it seemed to happen mostly to larger females which I don't need fewer of. Have since cut back to 20% 1-2x weekly and haven't noticed one since with a split carapace.
 

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Discussion Starter · #3 ·
I think this would be prudent, but if not overfeeding seems more than you should need to do. I was doing 50% weekly on my Osaka cubes but had occasional WRoD issues. Not on a large number of shrimp, but it seemed to happen mostly to larger females which I don't need fewer of. Have since cut back to 20% 1-2x weekly and haven't noticed one since with a split carapace.
I'm not over-feeding and keeping the tank tidy. I think my dosing and Seiryu stone cause the gradual TDS rise over the week so I feel compelled to change water to manage that. I think WRoD is from doing a water change that results into a sudden TDS increase. I wonder what can happen in my case of a TDS decrease.

I'm thinking a daily or every other day small water change. It's a 50G tank and probably 45G of total water, so I could change a 5G bucket a day and have minimal impact to water parameters while changing a substantial amount of water per week.
 

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snails are your friend
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@Asteroid I had a batch of Seriyu that jacked KH like Texas holy rock. It was suitable for nothing but rift lake fauna. I've been skeptical of purchasing any since. It's not a "type" of rock like feldspar or such that has general properties you can more or less count on being consistent. It's its own trade name that people try to sell anything with a similar structure for this hobby. I can't claim to have tested hundreds of batches or anything but some of it seems to be nearly pure lime.
 

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@Asteroid I had a batch of Seriyu that jacked KH like Texas holy rock. It was suitable for nothing but rift lake fauna. I've been skeptical of purchasing any since. It's not a "type" of rock like feldspar or such that has general properties you can more or less count on being consistent. It's its own trade name that people try to sell anything with a similar structure for this hobby. I can't claim to have tested hundreds of batches or anything but some of it seems to be nearly pure lime.
Yeah I know LOL, my KH went up to 16 the other day when I didn't keep up with water changes from a tap of 4. GH was also around 16. And your right batches can vary. Just looking at OPs numbers I didn't think a rise in the TDS based on those would be a problem. So far I haven't seen any effect on fish or critter in my tank.

I guess the silver lining of using Seiryu is that it might push you to keep up with water changes.
 

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Is that enough of a change in parameters to cause a problem or behavioral change with shrimp?
When I needed to make significant parameter changes to a tank several months back and asked here on the forum for suggestions about how to go about this, someone suggested not changing any parameter by more than 10% at once. I think that was a ballpark figure as a rough guide, and by no means set in stone or based on any particular scientific fact. However a 10% maximum change in TDS / GH / KH is what I now keep in the back of my mind for water changes. I think it's probably quite conservative and on the safe side, and obviously your RCS survived a ~25% TDS change. But at this ~10% level the shrimp don't seem to notice anything has happened. It's also quite an easy number to calculate and work with in your head without needing to resort to a calculator.

Just wondering, is there perhaps a way to 'invisibly' coat problematic stones with some sort of varnish or lacquer to prevent them dissolving into the water column and affecting parameters, but without affecting how they look?
 

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Discussion Starter · #9 ·
When I needed to make significant parameter changes to a tank several months back and asked here on the forum for suggestions about how to go about this, someone suggested not changing any parameter by more than 10% at once. I think that was a ballpark figure as a rough guide, and by no means set in stone or based on any particular scientific fact. However a 10% maximum change in TDS / GH / KH is what I now keep in the back of my mind for water changes. I think it's probably quite conservative and on the safe side, and obviously your RCS survived a ~25% TDS change. But at this ~10% level the shrimp don't seem to notice anything has happened. It's also quite an easy number to calculate and work with in your head without needing to resort to a calculator.

Just wondering, is there perhaps a way to 'invisibly' coat problematic stones with some sort of varnish or lacquer to prevent them dissolving into the water column and affecting parameters, but without affecting how they look?
I like the stones and am willing to live with the consequences. They can't be removed without wrecking the whole thing. I would be changing water weekly anyway.

The effect seems to have slowed. I have not tested to see how far it would drive gH, but going from 12-14 gH in a 7-10 days is not that bad. kH is less effected, goes from 5 to 6.

I like the 10% rule. It's a good easy number and should be gentle on the shrimp. I was just reading that their cells can't handle osmotic changes like we vertebrates. If for example, TDS was suddenly increased, their body cells swell, and all within their shell. So that creates molting problems (in that case probably a forced molt before it was ready to molt). I notice the hobby shrimp breeders online post they hardly ever change water. In a well populated mixed tank with plants and nutrients you can't really do that, so 10% it is.
 
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