Rapidly dropping Alk, with only 3 frags in a 90g

I have experienced this too a much lesser degree on prior builds. I know that there are several biological processes that can cause this to occur, having said that, I have never experienced it like this, and I can't correct it.

I set this tank up like I have done all of my tanks, dry rock and "live sand", and biospira + ammonia. The tank finished cycling on Day 10. In those 10 days, the tank had dropped 1.3dkH to 7.3 dkH. Pretty normal in my opinion. I started ghost feeding the tank a small amount of pellets or mysis so I could maintain the bacteria population without adding ammonia (so I could add a few corals). I have been ghost feeding daily ever since. Here are my some notes and test results related to Alk/Calcium and any other significant changes.

Day 12:
Dosed brs 2 part equivalent to 1 dkH/7ppm calcium to try and reach 8.3 dkH and 420ppm Calcium
8 hours later, 8.4 dkH and Calcium 420ppm. over 1 hour

Day 18:
Alkalinity: 7.1 dkH (Hanna), 7.3 dkH (salifert) This is a 1.3 dkH drop in 6 days.
Calcium: 410ppm (Red Sea)
Magnesium: 1425ppm (salifert)

Dosed BRS 2 part equivalent to target 8.3dkH/420ppm Calcium over 3 hours

Day 19:
Added co2 scrubber (ph was between 7.9-8.1, raised ph to 8.2-8.37)
Added 3 torch frags

Day 20:
Alkalinity: 7.2 dkH (Hanna), 7.3 dkH (Salifert) This is a 1.1 dkH drop in 48 hrs
Dosed BRS 2 part to target 8.4 dkH/420ppm Calcium (assume calcium is balanced still) over 3 hours

Day 21:
Alkalinity: 7.0 dkH (Hanna), 7.0 dkH (Salifert) This is a 1.4 dkH drop in 24 hrs
Calcium: 400ppm (red sea)
Dosed BRS 2 part to target 8.3dkH/ 410ppm calcium, this time spread over 12 hours

3 hours later- Alkalinity 7.3 dkH (Hanna), 7.5 dkH (Salifert)

This is when I pretty much confirmed I was having significant precipitation issues by dosing too much or too fast. OR the soda ASH in brs 2 part was raising my pH too high and causing precipitation (Since my ph now stays between 8.2-8.37). I say pretty much because there are no signs of significant precipitation in my tank, no cloudy water, no crusty pumps or heaters, there is some precipitation on the bottom of my sump but does not look as significant as the amount of dkH I am losing. Regardless, I thought since i was ending up right back where i started i would just try a very slow addition of .05 dkH via kalkwasser drip (only .02 pH increase) overnight to gradually raise the dkH, and i would remove my co2 scrubber if it started getting too high.

That was last night, and this morning my Alk tested 6.5 dkH (Hanna) , 6.3 dkh (Salifert)

Neither test kit/reagents are expired and I even confirmed results with a brand new Red Sea Alkalinity PRO.

Thoughts? My theory is that this is precipitation that is just hidden somewhat and I simply need to lower my pH or use sodium bicarb instead of soda ash. Or, there is still a biological process occuring here that can be that powerful? Could there be something wrong with my saltmix or water? Diatoms cant consume alkalinity right? I am pretty confused.

Thanks!

 

Do you have much coraline algae?

 

No, as I said this is a brand new tank with dry rock (acid/lanthanum chloride cured pukani) and live sand (arag alive Fiji pink).

Zero coralline algae

 

I will also say that I've tested ammonia nitrite nitrate periodically throughout these 2 weeks and nothing out of ordinary since the cycle finished. I use 0 tds RO/DI but prior to that it is from a well and softner/treatment. Not sure if that can do anything as I just moved here and have always had city water.

 

Is it possible that having a 300w heater in a 1/3 chamber of a 40b sump is causing that significant precipitation when it kicks on shortly after dosing? The heaters are partially dusted. Temp is 78.0-78.2

I also am using 5L of siporax for the first time, is it possible significant denitrification is already occuring 20 days in and its lower dkH that much? I doubt it.....

I think ill try removing the Co2 scrubber and re-dosing once the pH has dropped a little. If that doesn't work I will also try some sodium bicarbonate instead of soda ash (even though pH never gets above 8.37). Just looking for some outside perspectives, thanks!

 

Thanks Randy, I did not realize new rock and sand could act as seed crystals for precipitation. Like I said I have experienced this before on prior builds to a much lesser extent. The big difference is in the past ive struggled with low pH (small apartments) and now I have gotten it up to 8.4 in my big house (not bragging just mean a lot less co2 lol). Also ive never used pukani. I'll take the co2 scrubber offline and add some more organics, then continue dosing and monitor daily. Hopefully that will slow it down a bit.

Thanks bud

 

Wow, I didn't realize the difference was that significant.

 

Wild, makes sense. PH dropped down from 8.2-8.4 to 8.0-8.2 by taking the co2 scrubber offline. Feeding extra as well. Dosed the same amount and it appears ive cut precipitation by more than half already. Hopefully these rocks/this sand will chill out on seeding crystals soon so I can raise my alk easier asap lol.

Thanks again

 

So the higher the PH the faster alk depleted? Someone please verify ?

 

BRS, during the BRS 160 series, made the claim that a higher pH might be the cheapest and most effective thing you could do to improve coral growth.

This kicked off a huge interest in CO2 scrubbers and threads on increasing pH. Given the BRS160 was a new tank, and I *think* their claims where based off Alkanity usage, any chance some of that alk usage was actually percipitation rather than coral consumption?

When Alk consumption increases with a higher pH, how can the hobbist be confident it's due to coral consumption??

 

Yes, they definitely mentioned that in the video too though. He said that some of it could be precip, but they didn't see any obvious signs of that. Although the brs 160 was actually not anywhere close to as new as my tank when they added the scrubber.

I don't think you can just say "higher pH alk depletes faster" because there are many other factors at play. Having said that coral calcification should be easier/faster at higher pH for the same reason precipitation can increase.

The extensive precipitation I have experienced has only ever occurred for me in the first month or two of set up due to the new rock and sand.

If your alk consumption goes up with higher ph, you can tell if it is primarily from corals if there are no signs of precipitation and there are obvious signs of increased growth rates in the corals. You could easily have both precipitation and increased growth rates in corals as well.

 

I can say that on my last build when I increased my ph from 7.8-8.0 to 8.0-8.2 with daily kalkwasser dosing, I saw significant improvement in growth. This was also likely due to increased alk stability however.

 

Thanks for the extra info, it'd been awhile since I'd see it.

I think what allowed them to say that is they had a baseline alkalinity consumption at one pH, with nothing else changing in a 'stable' system, when the pH increased, the alkalinity consumption also increased leading them to assume the increase was 100% consumption related. However, if the precipitation is really crystals in the sand bed, how can you tell?? It was the first time their sand bed encountered higher pH, yes? It wouldn't be as easy as noticeable precipitation on pumps or glass. Over the course of a month you might figure it out, alkalinity consumption returns back to the lower value or you don't notice growth.

But given how dynamic our tanks are (adding more frags, frags become bigger) it seems potentially easy that you overstated the impact, what allowed them to say potentially cheapest and most effective way to increase growth was higher pH, so maybe it's helpful, but not as major as initially believed??

My takeaway and I think many others from that video made us look at pH much more seriously, just wondering if potentially it might have been overstated?

 

Keyword potentially. Like I said before, they never assumed that it was 100% consumption related, they said it could have been precipitation. I think the sand and rock precipitation mainly happens in the early stages of a tank and then some sort of equilibrium is established. Randy would have to answer that though. So if they had increased alk consumption it's likely a portion of that was related to growth imo (since they didn't see significant signs of precipitation elsewhere).

I do agree that the title of the video was overstated though, while its possible it could significantly boost your growth, it can be expensive if you constantly have to switch out media, and you can't exactly prove that's why your seeing increased growth. Sometimes corals settle in and just take off.

I think the reason they were confident enough to post the video and say that is because all of their office tanks have put co2 scrubbers online recently and seen improvement in growth rate, not just the brs 160.

 

Fair point and I fully trust BRS. But that video sure did launch a bunch of sales of CO2 scrubbers + people running skimmers airline hoses out the window. This thread was insightful to me, because I assumed I could visually detect precipitation, but a sand bed can mask it to a degree. Once the tank matures, it will be less of an issue. I latched onto that phrase 'most effective' more than 'potentially', but that's on me not BRS.

 

Yes, alk stability seems huge. The quest for higher pH is probably correlated to a more stable pH and more stable alkalinity. And stable is always good