Mid-cycle alkalinity settling at 6.3

[eonblue]

This is my first aquarium, and I'm currently 20 days into cycling using Dr. Tim's products. Probably a few days out from finishing.

One thing I've noticed the last couple of weeks is that my alkalinity will always settle at 6.3. I'll add B-Ioniq and see it go up to 7.5, then drop right back to 6.3 in two days and stay there. I know the ammonia eating bacteria will use alkalinity, but I have been at 0 ammonia for a week while waiting for nitrites to process, and still alkalinity will fall shortly after a dose.

My current theory is that the AquaForest stone mix I used on the rocks is pulling carbonate out of the water. Calcium has not dropped, and magnesium went from 1300 to 1240 over 10 days. Any other ideas about what might be causing this pattern?

I know it's not causing any issues, and I don't intend to add corals for a couple of months; it's mostly just curiosity. Also, I'm using Hanna colorimeters for testing.

 

[Fish Fan]

It's normal for Alk to fall during a cycle as the bacteria can consume some of the Alk ions. I wouldn't worry about Alk until you're ready for corals.

And, if your ammonia is zero, you're cycled. The nitrite is non-toxic in saltwater tanks, so there's no need to wait for it to zero out

Good luck with your tank!

 

[eonblue]

Thanks! I'm not worried; it's just weird that it sticks at 6.3. Like whatever is taking alk from the water stops when it gets to 6.3. I'm still learning about the chemistry though, just curious.

 

[bryster]

Thanks! I'm not worried; it's just weird that it sticks at 6.3. Like whatever is taking alk from the water stops when it gets to 6.3. I'm still learning about the chemistry though, just curious.

What's a good number to aim for ?

 

[eonblue]

What's a good number to aim for ?

Ideally around 8 but it's more important to keep it stable when you have coral. My tank is still empty so not worried about big swings. I'm sure once the biome is established I won't see the drastic drop after dosing.

Calcium, Magnesium, and pH all work together with alkalinity in ways I don't understand yet.

 

[Fish Fan]

Calcium, Magnesium, and pH all work together with alkalinity in ways I don't understand yet.

pH is dependant on alkalinity (which is a group of ions) and carbon dioxide in the tank and in the air around the tank.

Alk, Calc, and Mag are the "big three" for coral care, but if like most newer reefers you're planning on keeping easy going soft corals, mushrooms and Zoas, you really don't need to worry much about testing these parameters. Soft corals don't consume these elements nearly as fast as their stoney coral cousins because they are not building a calcium carbonate skeleton. Just by doing regular, partial water changes, you'll keep these parameters well in line for a softy tank, no test kits required

If you do want to did further into the chemistry, this is a pretty good video to start with:


I hope that helps!

 

[Decamicron Labs Verified Sponsor]

I should note that while nitrite is a lot less toxic to saltwater fish than freshwater fish, it still is toxic. I would be comfortable with hardy fish like damsels, but I would avoid more sensitive fish such as wrasses, angelfish, and anthias.

 

[Fish Fan]

I should note that while nitrite is a lot less toxic to saltwater fish than freshwater fish, it still is toxic.

This is incorrect

Nitrite can never reach toxic levels in a reef aquarium. Please see this post and the linked article from Randy Holmes-Farley for more information:
https://www.reef2reef.com/threads/nitrite-toxicity.402708/post-4805029

I hope this helps!

 

[Decamicron Labs Verified Sponsor]

Your link is broken. I'm guessing you are referring to the chloride uptake argument (this is noted on our homepage decamicronlabs.com), and if the assumptions are right, would be correct.

However, there is some aspect of biological reality that is being ignored. I have had new cycles stall at several ppm nitrite. I also have had fish have mass lethargy and die offs in tanks without detectable NH3 but 1ppm nitrite.

I followed this advice before and have been burned by it. It is simply bad advice.

 

[Fish Fan]

Your link is broken. I'm guessing you are referring to the chloride uptake argument (this is noted on our homepage decamicronlabs.com), and if the assumptions are right, would be correct.

The link works fine for me, it should take you to a post from Randy Holmes-Farley confirming that nitrite is non-toxic in saltwater tanks, and he includes a link to his article with a greater explanation, and indeed it is from an interplay of chloride ions that prevent nitrite poisoning:
https://www.reef2reef.com/threads/nitrite-toxicity.402708/post-4805029

For anyone who does not know, Randy Holmes-Farley is a PhD level chemist who has been a reef tank guru for probably 30 years now. Randy's advice is highly regarded in the reefing community.

However, there is some aspect of biological reality that is being ignored. I have had new cycles stall at several ppm nitrite. I also have had fish have mass lethargy and die offs in tanks without detectable NH3 but 1ppm nitrite.

As I'm sure you know, the nitrogen cycle is a biological process, and it simply can't stall; that's a common misconception. What does seem to happen is that the nitrite oxidizing bacteria can to take longer to establish than the ammonia oxidizers. This can give the impression of a 'stalled cycle'. And as noted, we are not concerned with nitrite at any level in a reef tank.

I followed this advice before and have been burned by it. It is simply bad advice.

As mentioned above, Randy's advice is widely trusted in the community. He has given this advice about nitrite countless times, and I have done the same, and no one has come back to complain to me. If you added fish to a new tank with some nitrite and they did not make it, something else was at play, it's wasn't the nitrite

I will add, if someone feels better about waiting for the nitrite to zero out before adding fish, that's fine with me. But it's incorrect to say that nitrite is toxic in marine systems, and that one should or must wait for it to zero out.

 

[Decamicron Labs Verified Sponsor]

I actually did some digging into this and you may be correct. The link is broken, but I was able to find the original article. The PAN database number now refers to a different chemical, but I was able to locate the listing for sodium nitrite using the wayback machine. A lot of those references weren't logged, but I was able to find some new papers like this:

https://link.springer.com/article/10.1007/s10499-015-9965-9

This is very different to what I have experienced. I may need to look into whether my Seachem badges are faulty.

Thank you for prompting me revisit this.

 

[Decamicron Labs Verified Sponsor]

The link works fine for me, it should take you to a post from Randy Holmes-Farley confirming that nitrite is non-toxic in saltwater tanks, and he includes a link to his article with a greater explanation, and indeed it is from an interplay of chloride ions that prevent nitrite poisoning:
https://www.reef2reef.com/threads/nitrite-toxicity.402708/post-4805029

For anyone who does not know, Randy Holmes-Farley is a PhD level chemist who has been a reef tank guru for probably 30 years now. Randy's advice is highly regarded in the reefing community.


As I'm sure you know, the nitrogen cycle is a biological process, and it simply can't stall; that's a common misconception. What does seem to happen is that the nitrite oxidizing bacteria can to take longer to establish than the ammonia oxidizers. This can give the impression of a 'stalled cycle'. And as noted, we are not concerned with nitrite at any level in a reef tank.


As mentioned above, Randy's advice is widely trusted in the community. He has given this advice about nitrite countless times, and I have done the same. If you added fish to a new tank with some nitrite and they did not make it, something else was at play, it's wasn't the nitrite

I will add, if someone feels better about waiting for the nitrite to zero out before adding fish, that's fine with me. But it's incorrect to say that nitrite is toxic in marine systems, and that one should or must wait for it to zero out.

I'm very well aware about the cycle, thanks. The link inside the link still doesn't work :)

 

[Fish Fan]

I'm very well aware about the cycle, thanks. The link inside the link still doesn't work :)

I was not trying to condescend, I know you know what a biological process is

I'm not sure what to say about the link, both work just fine for me. Do you have a pop-up blocker installed?

Here's the direct link to Randy's article if anyone is interested:
http://reefkeeping.com/issues/2005-06/rhf/index.htm

 

[Decamicron Labs Verified Sponsor]

I'm not sure, it takes forever to load and when it does I get a popup saying the connection is not secure.

I would use the wayback machine: https://web.archive.org/web/20260115204636/http://reefkeeping.com/issues/2005-06/rhf/index.htm

 

[netoultra]

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