Water parameters

[MaisyMoose]

It does sound as though something has changed the pH of the tank water.

Could you test some freshly run tap water with both testers, then leave a glass of water to stand overnight and test that next day with both testers. That will give a baseline to work with.

Then can you tell us about your tank, please. So that we have all the data together in one place -
How big is the tank, volume and dimensions.
What species of fish and how many of each.
Nitrate level in the tank water and your tap water (so we know how much comes from the tap water and how much is being made in the tank)
How often do you do water changes.
How much water do you change each time.
Do you have live plants - what type.


Do we know how hard your tap water is? If you are on mains water, does your water provider's website list your hardness and alkalinity (that's what water providers call KH)?


The photo from a month or so ago shows your pH at around 7.4. It's still at the lowest colour on the high range so no higher than that.
Usually, things like decor or substrate raise pH not lower it as limestone rock or crushed coral decor/substrate increase both hardness and pH. Few things lower pH, maybe almond leaves or peat if the water is fairly soft to start with. But when the water is soft, if insufficient water changes are done, or the tank is very overstocked, the acids produced in the tank can use up all the KH and allow the pH to drop.
That's the reason for all the questions, to help us work out what's going on.

I appreciate the help and the questions — thank you! I want to learn and get this right!

I currently have a 15 gallon tank.
Two (pregnant) female platys and a male platy
Two rasboras
Three Cory catfish
Two shrimp
Three young female guppies
A dozen or so small platy fry
Lots of ramshorn snails—which I’ve been removing as well
* I have been removing platy fry into a nursery tank— have moved a dozen (hard to catch)!

Dragon stone
Driftwood
Java moss

Water changes— 20-30% weekly—sometimes bi-weekly bc of fry. I gravel vacuum too.

Base test from tap between 6.6-6.8

I will test overnight water from tap for pH.

I also have everything to upgrade to a 40 gallon breeder aquarium.

I’m sure the water here is soft.

Thank you

 

[MaisyMoose]

 

[MaisyMoose]

pH directly from tap

 

[Byron]

From the photo, I would call that 6.8 pH. Everything seems to be normal here. The livebearers will not be doing well and they will weaken and die. The soft water species though will flourish.

 

[MaisyMoose]

From the photo, I would call that 6.8 pH. Everything seems to be normal here. The livebearers will not be doing well and they will weaken and die. The soft water species though will flourish.

What can I do?

 

[Byron]

What can I do?

Return the livebearers if this one tank is all you have or can have. Or start a second tank for livebearers. You can use a calcareous substrate (increases GH/KH/pH) and prepare water for water changes so parameters are close. I did this back in the 1980's for my mollies.

There are so many suitable and colourful fish for soft water, you will never be at a loss. Tetras, rasboras, catfish... .

 

[Naughts]

What can I do?

My choice would be -
Once the 40g is ready you could transfer the cories and rasboras, increase their shoals significantly then look at other soft water species if you wish to add more.
Keep the 15g for the livebearers and use a calcererous substrate.