CRS, TDS and GH

[jameson_uk]

Hi all, I think they are selected form of Cherry Shrimp (Neocaridina davidi), in which case they will do better in harder water.

cheers Darrel

They are a slightly different type rather than through selection I believe (https://upload.wikimedia.org/wikipedia/commons/3/37/Neocaridina_family_tree.jpg) but probably the same (I think there is some debate whether they are different species or not). Either way they are basically the same

Most shrimp owners seem to think a GH of 12 is too high and suggest 8-10 being acceptable. GH is calcium and magnesium right? If UK doesn't have much mg in water would this mean that a UK GH of 12 would potentially have more calcium than a US GH of 12???

I believe it is the high levels of calcium which make their skin too tough which then gives them issues molting.

 

[jameson_uk]

Ok I lost another with a failed molt and presume I have lost a few more that are hidden in the background.

Is TDS important? No there seems to be one school that says TDS is the be all and end all for shrimp and another which says it doesn't really matter.

I had always just assumed those obsessed with TDS were using RO water and hence TDS would make sense and a lot of other people are just using TDS as a proxy for their GH and calcium levels.

I did however read something about osmotic pressure and this being important for molting and this suggested that a higher TDS (no matter what it is made up of) can cause issues.

My TDS is now about 300 after I mixed in some deionised water. Tap is normally about 320 and this was measured the day after water change when I added ferts and prime which seems ok to me. I know a lot of people seem to have happily breeding RCS colonies in even higher TDS but wondering whether it is worth trying to reduce TDS to around 200 and try and get the colony going and then slowly switching back to 100% tap???

 

[keano]

Ive never lost a CRS i've no idea what my tap water comes out at. Tap water goes straight in untreated.

The only 2 parameters i check once a week is TDS and pH. My TDS is what i used to determine when i change the water when gets above 150-170 i change half a tank.

pH stays around 6 due to CO2 injection and substrate

 

[sparkyweasel]

They are a slightly different type rather than through selection I believe (https://upload.wikimedia.org/wikipedia/commons/3/37/Neocaridina_family_tree.jpg) .

Can you make any sense out of that diagram?

Most shrimp owners seem to think a GH of 12 is too high.

I suspect that most shrimp owners just put a few cherries in their tank with tap water and never think about TDS.
Mine lived, moulted and bred at 18°GH before I moved house. 12°GH now.

 

[Barbara Turner]

Could the shrimps have access to to much protien?
I know this can also cause problems moulting.

Just checking the obvious, you have checked Ammonia and nitrite levels both will quickly kill off shrimps.

I've killed cherries with liquid carbon but I was spot dosing just under twice recommend as I had a algae problem.

Is it time to buy a cheap RO filter off fleabay and see if it helps, it's alot of extra faffing if you can advoid it.

 

[jameson_uk]

Ammonia and nitrites both 0. I have not dosed any liquid carbon with these shrimps.

I have mainly fed leaf based feed (and not much of that) so I don't think they have had much protein.

With this heatwave the temp has risen to ~23°C but they were dying before when it was 21°C.

Had a bit of a scan last night and removed another couple that had died trying to molt.

I could only find a couple of shrimp out of the 10 I added.

After £80 I think I might have to give up on shrimps....

 

[jameson_uk]

Came across https://skfaquatics.com/forum/topic/4228-gh-camg-ratio/ which talks about the ca:mg ratio being right. This sounds plausible but I guess that is the whole point of call my bluff.... 🙄

My thought has always been that most of the hardness here is Calcium Carbonate so it did make me wonder whether all the Calcium isn't available to the shrimp as there isn't enough Magnesium.

Anyway I couldn't quite figure out the chemistry. It says
Mg = ((GH*17.86) - (Ca*2.5)) /4.1

I know my GH comes up as 12 and for a ball park figure I looked at https://www.south-staffs-water.co.uk/household/my-water-supply/water-quality/water-hardness which has a number of different values for calcium / magnesium / hardness. My are Sutton Coldfield says 62 ppm Calcium and 10.82 ppm Magnesium which gives ~ 6:1 ratio.

However knowing my GH is 12 and plugging in the calcium ppm of 62 give a ratio of something like 4.2:1

Then further it talks about Calcium levels saying
100ppm = 100/17.9 = 5.6dH
But assuming my Calcium levels are ~62ppm this doesn't make sense as GH is 12 (11.2 on water company report)

I get a bit lost but I think the GH * 17.86 is to convert this into CaCO3 ppm? Then I guess CaCO3 is 2.5 more than Ca . So taking away gives the ppm of some sort of Mg and 4.1 is the conversion factor to get back to actual Mg?

The GH seems to match water company report and I suspect the calcium levels are probably indicative so just trying to figure out what ballpark my actual ca:mg ratio might be in.

Anyone who actually understands the chemistry care to input? @dw1305 ?

 

[Edvet]

Ca: Mg ratios are more influenced by food, High quality food will supply the necessary minerals.