Wacky pH from crushed coral

[fishtime!]

So I'm getting a tank ready for a betta fish the cycling looked complete to me, but the pH was 6.0 (or maybe lower because the kit only measure to 6), and I wanted to get the pH up to around 7 at least.

I read that you can used crushed coral and I actually happened to have a piece of coral skeleton on my desk. So I put it in, the pH went up some but came back down, then I crushed it and the pH skyrocketed so I took most of it out. I'm attaching a picture of the pH measurements and when I did things.

Anyways, my point is - am I being nuts trying to find the right portion of coral? Should I be waiting longer before making adjustments to let the carbonate cycle work itself out? Should I bite the bullet and just go buy some crushed coral?

Tank description:
Tank size: 20 gallon tall
Substrate: bottom layer fluval bio stratum, top layer sand
decorations: dragon rock and driftwood
Plants: anubias, amazon frogbit, java moss
Parameters: ammonia - 0 , nitrite - 0, nitrate - .5
Tank inhabitants: a couple pond snails that hitch hiked on the plants
Thanks in advance!

 

[Lcc86]

Your pH level seems pretty good for a betta tbh, I wouldn't worry about trying to raise it any higher

 

[Uberhoust]

It is a matter of surface area. Crush coral has a large surface area so it will affect the water more quickly. Really, I don't think you should be using coral in your betta tank at all. Using substrate to control pH will likely never work out, as the rate of change decreases over time as the surface gets exposed to the water. You will always be trying to find the ideal mix. I haven't heard of any material that will buffer the pH to 7.0 without having to be constantly monitored.

I would also be concerned about why the pH is dropping so quickly. It almost seems like there is something in your tank that is driving the pH down. Simply removing the coral should not affect the pH in the existing water that rapidly.

The good thing is you don't have the fish in there yet. If it were me I would probably start with a large water change. If you are focused on 7.0 then likely you will have to remove the Fluval Bio Stratum because that will be pushing the pH lower, though typically not too low.

As the previous poster mentioned 6.0 is likely ok. Having a stable pH is more important than a pH at 7.0.

 

[TwoTankAmin]

Use it in a small mesh bag in the filter. As it dissolves, you can replenish it. Using less coral means less KH raising as there will be less volume/surface area. A little trial and error and you will figure out how much coral is what you need.

Hardening Your Water (Raising GH and/or KH)

The following measurements are approximate; use a test kit to verify you've achieved the intended results. Note that if your water is extremely soft to begin with (1 degree KH or less), you may get a drastic change in pH as the buffer is added.

To raise both GH and KH simultaneously, add calcium carbonate (CaCO3). 1/2 teaspoon per 100 liters of water will increase both the KH and GH by about 1-2 dH. Alternatively, add some sea shells, coral, limestone, marble chips, etc. to your filter.

To raise the KH without raising the GH, add sodium bicarbonate (NaHCO3), commonly known as baking soda. 1/2 teaspoon per 100 Liters raises the KH by about 1 dH. Sodium bicarbonate drives the pH towards an equilibrium value of 8.2.

Bear in mind that sodium in any serious amount may not be a good idea longer term. I used to run a bag of CC on my high tech planted tank with CO2 pumped in. it would drop the KH and yo avoid a pH crash I ran a bag with abut 1/2 cup of CC in the filter.

The way the CC etc, work is when the water is acid it causes the coral to dissolve. The mortr acid the water the more and faster the coral dissolves.

I am not a chemist so I am not sure this will work. I hnow how to do diluted testing which involves use more water for the test and then dividing the result. The reverse of this would be to add more drops and thendived the result. So if you add twice as many drops you would divide the resulting number by 2. You can use and number of extra drops as mong as you divide the result by the same factor.

The API kits uses 3 drops. is you use 4 that is 1/3 more so divide the result by 1.33, use 2 drops and it becomes divide by 1.67. 6 drops is double and you then would be divide by 2.

The theory is that by using double the drops it should give double the reading. The only issue is the normal range API test stops at 7.6 so if you hit that you are again against the wall. So, Start with 4 drops. and if that doesn't read over 6, then go to 5 drops etc.

 

[MaloK]

With your fluval bio stratum you will need a little more buffering.

 

[Colin_T]

Crushed coral, limestone, sandstone and shells will buffer the pH to 8.5 depending on how much is in the tank.

Bettas naturally occur in soft acidic water (GH below 100ppm and pH below 7.0). There is no reason to add crushed coral to a Betta's tank.

 

[fishtime!]

Use it in a small mesh bag in the filter. As it dissolves, you can replenish it. Using less coral means less KH raising as there will be less volume/surface area. A little trial and error and you will figure out how much coral is what you need.



Bear in mind that sodium in any serious amount may not be a good idea longer term. I used to run a bag of CC on my high tech planted tank with CO2 pumped in. it would drop the KH and yo avoid a pH crash I ran a bag with abut 1/2 cup of CC in the filter.

The way the CC etc, work is when the water is acid it causes the coral to dissolve. The mortr acid the water the more and faster the coral dissolves.

I am not a chemist so I am not sure this will work. I hnow how to do diluted testing which involves use more water for the test and then dividing the result. The reverse of this would be to add more drops and thendived the result. So if you add twice as many drops you would divide the resulting number by 2. You can use and number of extra drops as mong as you divide the result by the same factor.

The API kits uses 3 drops. is you use 4 that is 1/3 more so divide the result by 1.33, use 2 drops and it becomes divide by 1.67. 6 drops is double and you then would be divide by 2.

The theory is that by using double the drops it should give double the reading. The only issue is the normal range API test stops at 7.6 so if you hit that you are again against the wall. So, Start with 4 drops. and if that doesn't read over 6, then go to 5 drops etc.

Thanks so much! This was really helpful and I did feel a bit like a chemist yesterday...

 

[fishtime!]

Crushed coral, limestone, sandstone and shells will buffer the pH to 8.5 depending on how much is in the tank.

Bettas naturally occur in soft acidic water (GH below 100ppm and pH below 7.0). There is no reason to add crushed coral to a Betta's tank.

Thanks! Yah I think I was really overthinking this, I'm taking the coral out and leaving it alone to stabilize. I also watched a video of people catching Bettas in the wild and they were at 5.0 pH haha

 

[fishtime!]

With your fluval bio stratum you will need a little more buffering.

tbh wish I had never added it to the tank - thought I needed it for the plants but the ones on driftwood or just in the sand are doing better, and its an absolute mess anytime i wanna move something or clean. Thanks!

 

[fishtime!]

It is a matter of surface area. Crush coral has a large surface area so it will affect the water more quickly. Really, I don't think you should be using coral in your betta tank at all. Using substrate to control pH will likely never work out, as the rate of change decreases over time as the surface gets exposed to the water. You will always be trying to find the ideal mix. I haven't heard of any material that will buffer the pH to 7.0 without having to be constantly monitored.

I would also be concerned about why the pH is dropping so quickly. It almost seems like there is something in your tank that is driving the pH down. Simply removing the coral should not affect the pH in the existing water that rapidly.

The good thing is you don't have the fish in there yet. If it were me I would probably start with a large water change. If you are focused on 7.0 then likely you will have to remove the Fluval Bio Stratum because that will be pushing the pH lower, though typically not too low.

As the previous poster mentioned 6.0 is likely ok. Having a stable pH is more important than a pH at 7.0.

Thanks! Yah I've had some tanks before that have done poorly so I'm really trying to do everything right and taking a lot of time before adding a fish. I think I've been overthinking this - I'll remove the coral, do the water change, and just let it stabilize

 

[fishtime!]

Thanks! Yah I've had some tanks before that have done poorly so I'm really trying to do everything right and taking a lot of time before adding a fish. I think I've been overthinking this - I'll remove the coral, do the water change, and just let it stabilize

Also just and fyi - the pH in my tank was "changing so rapidly" because I wasn't washing out the testing vials between tests . rookie mistake(which I am lol).

 

[Essjay]

The nitrite test tends to stain the glass if it's not rinsed straight away. I use a paper hanky (kleenex) screwed into a rod shape and pushed into the tube to make sure there's no deposit left.

 

[Uberhoust]

Also just and fyi - the pH in my tank was "changing so rapidly" because I wasn't washing out the testing vials between tests . rookie mistake(which I am lol).

That is great, an easy fix.