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1.5 PH Swing / 0 KH

Aquastu

Seedling
Joined
24 Apr 2019
Messages
8
Location
UK
I seem to be having issues with the PH/KH of my water, directly relating to my CO2 schedule and starting to think it could be the reason behind 2 amano shrimp deaths.

  • It is a 30L cube, heavily planted and running for about 3 months now.
  • Injecting pressurised CO2 to 25PPM (on @7AM off @3PM - Light on @9AM off @5PM )
  • 50% WC Weekly w/ 10% midweek top up
  • Tropica Specialised ferts
  • Tropica Plant Growth Substrate
  • Tropica Soil Powder
  • 2/3 inches of white sand in the foreground only for aesthetic

I am testing my waters with a NT Labs test kit and a supporting electronic PH tester.

Tap water in my area (North West England) is moderately soft:
  • PH can vary from 6.8-7.0
  • 4DKH typically
  • 7 GH
Aquarium water
  • PH registering at 5.5 at peak afternoon near full CO2/light period(~3PM) and will eventually normalise to approximately 6.8-7
  • 0DKH on NT Labs Test kit (1 drop immediately yellow) and will range from 0-4DKH outside of CO2/light period

Clearly due to low KH in the water in my area, is allowing for the CO2 to plummet the PH.

I am concerned for my shrimp's well-being and the beneficial bacteria in my tank.

I have read up upon adding either a chemical or natural PH / KH booster but seem to find conflicting advice regarding the Tropica substrate burning out by holding on to the minerals - is it a case of taking the lesser of the 2 evils?
 
Last edited:
Hello,
Shrimp do not really care about pH or pH swings. What's killing them is the CO2, which is the most toxic component we use.
Reduce your CO2 injection rate or reduce the amount of time the CO2 is being injected.

Cheers,
 
Hi @Aquastu

I have a few observations and comments below:

Injecting pressurised CO2 to 25PPM (on @7AM off @3PM - Light on @9PM off @5PM

How did you arrive at the 25 ppm figure? Is this using a pH/KH/CO2 chart? Do you use a drop checker? If so, which one? Most drop checkers are aimed at an optimum CO2 concentration of 30 ppm but the most recent units from JBL have reduced this figure to 20 ppm.

I presume the above should read 'Light on @9AM'?

I am testing my waters with a NT Labs test kit and a supporting electronic PH tester.

Who is the manufacturer and what model is your pH tester? Has your pH meter been recently calibrated?

PH registering at 5.5 at peak afternoon near full CO2/light period

There is a real risk of killing off nitrifying bacteria at the above pH.

Which aquarium light are you using? Is it dimmable? More light means that plants need more CO2 and more nutrients/fertilizers.

JPC
 
Last edited:
Thanks everyone for your input, valued as always.

I have turned down the CO2 and now just watching to see how everything responds.


Hello,
Shrimp do not really care about pH or pH swings. What's killing them is the CO2, which is the most toxic component we use.
Reduce your CO2 injection rate or reduce the amount of time the CO2 is being injected.

Cheers,

I have turned it down significantly - running around 1 bubble every 3 seconds. Drop checker checker still lime green.


Perhaps some useful reading :)

Shrimp and CO2

Shrimp and various water parameters (I used Shrimp Water Parameters as the Search terms)

And of course, Shrimp Diseases
(often easier visualized through photos and video)

There are other shrimp related sites of course, and The ShrimpSpot is one of my favourite shrimp forums (which are useful as you’ll get varying views/opinions)

Thank you - interesting read regarding Shrimp and CO2. As above turned CO2 down slightly and monitoring activity over the next few weeks.



Hi @Aquastu

I have a few observations and comments below:



How did you arrive at the 25 ppm figure? Is this using a pH/KH/CO2 chart? Do you use a drop checker? If so, which one? Most drop checkers are aimed at an optimum CO2 concentration of 30 ppm but the most recent units from JBL have reduced this figure to 20 ppm.

I presume the above should read 'Light on @9AM'?



Who is the manufacturer and what model is your pH tester? Has your pH meter been recently calibrated?



There is a real risk of killing off nitrifying bacteria at the above pH.

Which aquarium light are you using? Is it dimmable? More light means that plants need more CO2 and more nutrients/fertilizers.

JPC

CO2 Art drop checker with a small colour chart. I have turned down the CO2 and it has definitly turned more Lime green as opposed to pale green.

Lights - using an APS LED 14w/7500k light on my small tank currently, non dimmable. Lights come on at 9AM you are correct, I have amended this!

Its a cheapo £10 PH tester that I am using in conjunction with an NT labs tester. I know these can be innacurate, but again using both to give a 'round about' prediction of what the PH should be.

Lights - using an APS LED 14w/7500k light on my small tank currently, non dimmable.
 
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