Impact of Heterotrophic Bacteria on Alkalinity?

[ClutchCityReefer]

I've been dosing Dr. Tim's Waste Away (a form of Heterotrophic Bacteria) to combat a cyano outbreak in my newly established reef tank. I've noticed recently that my alk is surprisingly low - I've tested multiple times to make sure no user error and then started dosing and have seen an increase. I have brought my alk from 4.1 dkh yesterday to 4.9 dkh this morning, when I continued my dosing schedule on a slightly heavier basis (instead of 50mL spaced out over the day like yesterday I am doing 60 mL today).

I am trying to pinpoint the cause of this decrease and I keep thinking it is the bacteria (I have no LPS/SPS). The bacteria does significantly lower my pH (I think both because of the bacteria's natural processes and because I turn off my skimmer with co2 scrubber) and based off my research I understand this could lead to alkalinity depletion. Further, I've tried to do some reading on this topic and it seems like some bacteria depletes dkh while some adds to it. Am I safe to assume that heterotrophic bacteria is one of the types that depletes alkalinity?

In other words, I am curious about the chemistry of heterotrophic bacteria and what it may be doing to my tank!

Thanks all for the help and for teaching, I like to learn!

 

[Chrisv.]

@DrTim can you weigh in?

 

[ClutchCityReefer]

Thanks, good idea @Chrisv. If anyone is wondering I use Tropic Marin Pro Reef Salt which is on the lower side to begin with (usually about 7dkh) but I haven't recently tested my water change water. I suspect running my system on the low side may be at least somewhat contributing to the dip to 4.1.

I would also like to add the Waste Away has been fantastic in my battle v. cyano. I haven't won the war yet but I can certainly see the light at the end of the tunnel.

 

[Chrisv.]

I was told that green micro algae actually takes up alkalinity. I had never thought much about it before because I always had live rock tanks with coralline already going. When I cycled my new tank the all started to drop as the green microalgae came.

 

[Chrisv.]

I LOVE waste away and refresh. Actually all of the Dr Tim's products that I have tried worked well for me.

Refresh and waste away used in accordance with Dr Tim's protocol helped me beat dinos in two weeks.

 

[ClutchCityReefer]

Nice! I was "fortunate" that my dino was wiped out by the cyano-scourge. At least that has been much easier to fight (I think).

 

[Nano sapiens]

Nitrification lowers alkalinity by releasing hydrogen ions (H+). So there's you connection with Dr. Tim's product.

Denitrification raises alkalinity by releasing hydroxide ions (OH-).

 

[ClutchCityReefer]

Gotcha, so heterotrophs are nitrifiers? I didn't realize that was the case, thanks!

 

[Nano sapiens]

Gotcha, so heterotrophs are nitrifiers? I didn't realize that was the case, thanks!

Technically chemolithotrophs. The majority of chemolithotrophs are chemolithoautotrophs, but not all.


Wiki Nitrifying Bacteria

Nitrifying bacteria​

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Nitrifying bacteria are chemolithotrophic organisms that include species of the genera e.g. Nitrosomonas, Nitrosococcus, Nitrobacter, Nitrospina, Nitrospira and Nitrococcus. These bacteria get their energy by the oxidation of inorganic nitrogen compounds.[1] Types include ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB)...

Not sure if 'Waste Away' contains nitrfying bacteria, or not.

 

[ClutchCityReefer]

Yea I didn't think it did, I thought Dr. Tim's other product did though (One and only).

 

[Randy Holmes-Farley]

There's no mechanism for heterotrophic bacteria to consume alkalinity except as they cause an increase in nitrate as they consume organic matter. If nitrate is not increasing substantially, then bacteria are not likely the cause of the alkalinity changes.

When organics are metabolized and nitrate is produced, alkalinity is depleted at a rate of 2.3 dKH for each 50 ppm of nitrate produced.

I discuss that process here:

When Do Calcium and Alkalinity Demand Not Exactly Balance? by Randy Holmes-Farley - Reefkeeping.com

 

[ClutchCityReefer]

Thanks Randy! Considering my nitrate just zeroed out I don't think that is it - I wonder what depleted my alk then?

 

[ClutchCityReefer]

Thanks again for sharing the article Randy - it's always great to learn. I haven't been on top of testing my calcium as I don't have stony corals. I didn't think that my calcium would be low given that I am anal about water changes but your article points out this may be the culprit for my depleted alk. I will definitely test my calcium as soon as I get some free time to leave the office!

Thanks again for all the help - I mentioned I zeroed out 2 days ago on nitrates but due to your help from prior I dosed the sodium nitrate and have it back to 2.4 ppm two days after the zero! Thanks to the community for helping as always!

 

[Randy Holmes-Farley]

Thanks again for all the help - I mentioned I zeroed out 2 days ago on nitrates but due to your help from prior I dosed the sodium nitrate and have it back to 2.4 ppm two days after the zero! Thanks to the community for helping as always!

You're welcome.

The flip side of that is that dosing nitrate adds alkalinity, even if the level is stable or zero, because it is constantly being consumed.

 

[ClutchCityReefer]

Makes sense. Is it true that if my calcium levels are too high that could also be driving down my alk?

 

[Randy Holmes-Farley]

Makes sense. Is it true that if my calcium levels are too high that could also be driving down my alk?

Some abiotic precipitation of calcium carbonate is normal at any calcium level, but higher calcium can slightly speed up that process. However, unless you added a lot of calcium, it is not high.

 

[ClutchCityReefer]

I haven't added any calcium, I just am totally not comfortable w/ the Hanna calcium checker and get readings all over the place (all high)...will give it a rest and try again in a bit

 

[ClutchCityReefer]

Do you think I should I continue dosing the alk buffer by the way? I picked up Fluval's Sea Alkalinity (made from pharma grade sodium carbonate, sodium bicarbonate and sodium borate) when I discovered the problem but should I pause until I figure out why alk is low?

I'm also almost out of the buffer so let me know if there is anything better you would suggest - it was after work when I discovered the issue and Petco was the only thing open.

 

[Randy Holmes-Farley]

If you believe the alk is really below 6 dKh, then yes, raise it.

Long term, a buffer incorporating borate is not best since it is not being consumed like carbonate and bicarbonate. I never understood why it is added, except perhaps as a marketing thing to make the product appear better than baking soda or washing soda (it isn't). .

 

[ClutchCityReefer]

Haha cool. Yes I feel confident in my alk testing, only one step and I've repeated tests multiple times and almost always get within 0.1 of prior test. Do you think I should just use baking soda?