How much API pH DOWN?

[MultipleTankSyndrome]

I am going to be dosing the API pH DOWN product on my tanks to lower the pH, but have been unable to find any dosing more specific than 2.5 mL/95 liters (or 2.5 ml/190 liters for larger tanks).
How much does this dose lower the pH? I'm looking to lower the pH from 7.6 to 5.8 in a 473 liter, 110 liter, and 38 liter, but don't want to lower it more than 0.2 over 24 hours to prevent shocking the fish (as per the recommendations on the bottle).
Thanks in advance.

 

[Rocksor]

Why not just use a test of 1 litre of water from your tank, and calculate from that? You're going to have to measure KH afterwards so make sure it doesn't lower it below 4 degrees.

 

[MultipleTankSyndrome]

Thanks, not sure why I didn't think of that.
The tip on KH is helpful though.

 

[Milingu]

The pH is always linked to the KH. Depending on your KH you might have to dose more or less to reach you required pH.
Since there are no further information from the manufacturer, only testing helps.
I would never change the pH without testing anyway. Especially when it comes to such a big change, the risk of getting too low is simply too big.

You should also consider what happens when you change the water. Can you treat the water outside the tank? Otherwise the fish get a big and therefore stressfull pH difference every time you do a water change.

 

[duanes]

The pH is always linked to the KH. Depending on your KH you might have to dose more or less to reach you required pH.

Agree, if you have a high Calcium Hardness (strong alkalinity, AKA buffering capacity) in your tap water, that calcium will simply eat up the pH down the moment, almost immediately as you add it.
This is why there are no stock rules, as there are many, many water types one city to the next.

I had high alkalinity in the lake Michigan sourced Wisconsin tap water, which is why I always chose fish that came from my local water type (pH 8, high mineral content), rather than trying to constantly alter the chemistry, water change to water change.
With the water I had, I could drip pH 4 lemon juice in it, and the lemon juice would immediately get neutralized.
I have always wanted to keep Uaru fernandezypeezi, but I didn't consider it doable. Beyond just pH, there were also all the other minerals to take into consideration, that were unphased by a pH lowering treatment. I believe an RO system would have been my only option to keep them healthy
Especially when there were scores of amazing Central and North American cichlids perfectly adapted to my "liquid rock" water type.

 

[MultipleTankSyndrome]

Re: treating the water when it's time for water replacements. I finally came up with strategies to do this, and if anyone knows of anything I'm overlooking it would be appreciated to let me know.

For the tanks I do water replacements on using buckets, I will take some old tank water and mix in enough pH DOWN to dose the percentage of the tank water I removed. The total volume of this pH DOWN solution will be divided equally among all the buckets that go back in, being mixed in before the bucket is dumped in.

For the tank I will use Python on, this is something that getting a Rubbermaid cattle trough to dechlorinate new water in before the Python puts it back in the tank is covered by. I simply need to dose said cattle trough with enough pH DOWN before it goes back into the tank.

 

[phreeflow]

What kid of fish are you doing this for?

It’s best not to mess with pH. Most fish can adapt so long as it’s stable. What they can’t handle are big swings in ph. And depending on the buffering capacity of your water, you risk spikes up and down.

Unless is a wild caught fish like a fernandezypezi, it’s better not to mess around with those chemicals.

If you must, get an RO/Di unit

 

[MultipleTankSyndrome]

Cardinal+green neon tetras, as well as pictus catfish and clown/black kuhli loaches. I'm pretty sure they are all wild caught, so while it would be great if they could, I don't know how well they'll do at 7.6.

As of right now, the pH has been lowered from 7.6 to 7.4. I'll recheck that pH 24 hours after I lowered it, and if it remains constant, I'll proceed to 7.2 (not lowering it any more than 0.2 in 24 hours as per API recommendation). If the buffering capacity of the water is sufficient for the water to have risen from 7.4, I'll cease further doses.

Also small update in regards to how much pH will be dropped: It is actually going to be from 7.6 to 6.8 for the catfish and loaches, plus 7.6 to 6.2 for the tetras.

Have been looking into an RO/Di unit in the event the water softener won't drop the pH adequately and safely. But thanks for the suggestion.