Stabilizing PH and ALK

[mikemathis555]

Since I’ve added some Zoa frags to my tank, I’ve had wild swings in dKh and PH in my Fluval 13.5G tank. I know with a small tank, this can occur, but any advice on how to stabilize this?

No ammonia or nitrite
Nitrate is between 5-10 ppm
No detectable phosphates (only have API kit so might not be catching the small amounts)
salinity is consistently 1.26-1.27
dKH has been fluctuating between 9 and 7.5
PH has been fluctuating between 7.8 and 8.4
I’ve not done anything to influence these numbers other than weekly water changes 10-20% and 5 Zoa frags.

I don’t think any of these numbers are concerning, but I’m concerned about dKH dipping too low and causing a PH spike into the danger zone.

Anyone have any tips?

 

[Randy Holmes-Farley Verified Community Expert]

Alkalinity doesn't fluctuate unless you are dosing or doing large water changes with a mix not matching the tank.. Generally, it trends downward. A better alk test might be the first step.

pH does rise and fall daily, and more aeration will reduce the pH swing. But your entire range is acceptable and not necessarily a problem.

 

[mikemathis555]

Alkalinity doesn't fluctuate unless you are dosing or doing large water changes with a mix not matching the tank.. Generally, it trends downward. A better alk test might be the first step.

pH does rise and fall daily, and more aeration will reduce the pH swing. But your entire range is acceptable and not necessarily a problem.

im using a Hanna dKH tester, so I trust those results. I’m understanding why the ALK is going downward, and why the PH raises. But I’m just concerned it’s going to cause an issue.

as an example, I went out of town for the weekend, and water parameters were fine when we left. Automatic feeder worked properly, but when we got home the dKH went from 8 to 7.5 and the PH shot up from 8 to 8.4. This was just from Friday afternoon to Sunday evening.

should I be concerned that the dKH will drop further and the PH shoot higher? Is there a natural limit to this inverse relationship?

 

[Randy Holmes-Farley Verified Community Expert]

Yes, alk may keep dropping and may soon need to be supplemented to maintain it.

Don't worry about the pH. pH does not EVER get too high on its own (meaning without high pH supplements).

 

[Reef.]

im using a Hanna dKH tester, so I trust those results. I’m understanding why the ALK is going downward, and why the PH raises. But I’m just concerned it’s going to cause an issue.

as an example, I went out of town for the weekend, and water parameters were fine when we left. Automatic feeder worked properly, but when we got home the dKH went from 8 to 7.5 and the PH shot up from 8 to 8.4. This was just from Friday afternoon to Sunday evening.

should I be concerned that the dKH will drop further and the PH shoot higher? Is there a natural limit to this inverse relationship?

I think you misunderstood the reply, you said fluctuates, which means goes up and down, your alk may drop when adding corals but unlikely to increase was the point I think being made.

That seems a very big drop for a few Zoas, my guess is your tank is new and the alk would be dropping anyway without the corals until it matures a little more.

I would test daily then dose to increase the alk the amount it drops daily, aim for maybe what your salt alk is, and try and keep it stable at that figure.

 

[mikemathis555]

Yes, alk may keep dropping and may soon need to be supplemented to maintain it.

Don't worry about the pH. pH does not EVER get too high on its own (meaning without high pH supplements).

ok good deal, that was my main concern was some crazy PH disaster.

 

[mikemathis555]

I think you misunderstood the reply, you said fluctuates, which means goes up and down, your alk may drop when adding corals but unlikely to increase was the point I think being made.

That seems a very big drop for a few Zoas, my guess is your tank is new and the alk would be dropping anyway without the corals until it matures a little more.

I would test daily then dose to increase the alk the amount it drops daily, aim for maybe what your salt alk is, and try and keep it stable at that figure.

Yeah, the fluctuating comes from my water changes replenishing Alk and reducing PH…but then it’s starts all over, too quickly for my liking. I think with @Randy Holmes-Farley reply about the PH my concerns are a bit muted.

 

[Cool tangs]

Here is some things to consider for stable dkh in my experience...

You need to test at the same time each day, this will help determine if you using more or less.

If your manually dosing or rely on water changes it will test high and drop off until the next dose or water change.

Your tank is small. you may want to consider a auto doser(great for stability, as you can dose over a 24 hour period) or up your water changes.

Sound like it boosts to 9dkh then drops to 7.5 by the end of the week. I'd be concerned about going from 7.5 to 9 dkh in one water change.

But also you have to consider your corals sps will be sensitive to the change. If no sps i wouldnt be too concerned, all though corals may be ticked off for a little bit at first.

I dont think zoas would take up much, your corals might now be settled and growing taking up more dkh.

Hope this helps

 

[mikemathis555]

Here is some things to consider for stable dkh in my experience...

You need to test at the same time each day, this will help determine if you using more or less.

If your manually dosing or rely on water changes it will test high and drop off until the next dose or water change.

Your tank is small. you may want to consider a auto doser(great for stability, as you can dose over a 24 hour period) or up your water changes.

Sound like it boosts to 9dkh then drops to 7.5 by the end of the week. I'd be concerned about going from 7.5 to 9 dkh in one water change.

But also you have to consider your corals sps will be sensitive to the change. If no sps i wouldnt be too concerned, all though corals may be ticked off for a little bit at first.

I dont think zoas would take up much, your corals might now be settled and growing taking up more dkh.

Hope this helps

thanks for the reply. I get my water from the LFS and their water test around 8.5-9.0 dKH and 7.8-8.0 PH. So I do see some swings for sure…my normal weekly water change is only 10%, but have done an occasional 20%.

I do test in the mornings before feeding, but did test in the evening on Sunday when I saw a big dip in ALK and increase in PH, so that obviously factors in too.

For this small starter tank, I wasn’t planning any SPS, only Zoas, softies, and maybe some LPS (not sure yet).