Can't keep my alkalinity raised, help wanted!

[AmatuerAuer]

Based on the information below, can you solve the riddle?

I have a 120g DT connected to a 40b frag tank and an Emerald 39 sump. I am dosing BRS two part on BRS peristaltic pumps running on an Apex controller. Mg is tested and dosed when needed (maybe monthly..)

Alk Program:
Fallback OFF
OSC 030:00/005:00/025:00 Then ON

Calc Program:
Fallback OFF
OSC 000:00/005:00/055:00 Then ON

*basically dose each for 5 mins an hour, 24x7 with a thirty minute offset between them.

Stock List:
2" acro
1" mille
3" stylo
4" birdsnest
2" birdsnest
x2 6 head hammer
2 head frogspawn
large torch
3 1" diameter monti caps
x7-10 acan colonies
bunch of zoa
4" leather

Fish are all in QT for another 2 weeks and have been for 2 months. I still put some mysis shrimp in once a week to feed the hermits, and coral banded shrimp.

I do weekly water changes of about 10%.

My goal levels:
Alk: 9.5-10
Calc: 430-450
Mg: 1350

I was dosing 2:30 an hour 24x7 but once alkalinity started dropping (which I attribute to growth) I upped it to 3min and then 4min and now 5min an hour. That increase occurred over the course of a week with ZERO impact on measured Alkalinity. I even manually dosed large amounts to raise it from 8 to 10dkh only to see it drop back down again.

What has me puzzled is that I doubled the dosing schedule with no impact and relatively quickly. I don't want to get carried away and all of a sudden fix the glitch and my Alk goes nuts.

Recent Measurements attached.

 

[Kenmx10]

From my experience, large swings in alkalinity usually result from overdosing. I would do a larger water change, let it sit for a couple days, then do 2 test 24 hours apart to try and determine how much Alk is really being consumed. Then start off with smaller doses and work your way up. For example, If it appears you are using 20 ml per day, I would start at 10 ml per day and see how that affects the Alk. Then slowly up the doses till you can determine the amount of consumption. Its hard to determine the amount of consumption while overdosing because much is lost in precipitation.

 

[AmatuerAuer]

Thanks Ken. I am cognizant of precipitation both when adding manually and when placing the ends of the dosing lines. There is limited/no precipitation so I am confident that I am not losing it there. My educated guesses:

1) The monti caps from 2-3 weeks ago added more than I anticipated to the uptake side of the equation.
2) The other corals have settled and are growing faster causing my input to be outpaced.
3) The live rock has finally been well seeded with Coraline which is again adding to the uptake side of the equation.

The idea of stopping all dosing and measuring the decline is an interesting one. Basically reboot the system. I measure often and use multiple kits and multiple tests to assure accuracy in the trends. All those precautions make the issue that much more confusing. I am testing Alkalinity every twelve hours to avoid getting caught off guard by a spike.

 

[Eggyoke]

Good thing about BRS 2 part is it's cheap, bad thing is you need a lot. For your water volume, if your tank looses 1 dkh a day you'll need to dose 85 ml of soda ash. From my experience, levels over 8 dkh you need to dose quite a bit more than just keeping it at 8. My suggestion is to leave it 8. That's within normal range.

 

[Eggyoke]

I try to adapt the balling method. Fauna Marin and Aquaforest suggest keeping the ALk at 8 max. Don't get caught up with more is better.

 

[Randy Holmes-Farley]

It is likely just some increased demand, but I also would not always assume that doubling the time doubles the amount dosed since the volume dosed per minute may drift over time.

There is also a negative feedback loop reducing any rise: higher alk leads to higher demand, dropping it back some.

 

[FlyinBryan]

Kalk in your ATO! Raise alk to what you need then add Kalk, it will help keep it more stable. Low tech but very reliable. All of my tanks run it! Good luck!

 

[AmatuerAuer]

Randy - Can you expand on the negative feedback loop? In my mind each organism has an optimal uptake rate and anything above or below that would either result in slowed growth and/or recession when taken to either extreme. Also, you are saying a peristaltic pump will 'drift' by dosing at a higher rate per min for the first 2-3 minutes than the next 2-3 minutes (for example) how do you account for this? The motor of the pump?

 

[Kenmx10]

T

The idea of stopping all dosing and measuring the decline is an interesting one. Basically reboot the system. I measure often and use multiple kits and multiple tests to assure accuracy in the trends. All those precautions make the issue that much more confusing. I am testing Alkalinity every twelve hours to avoid getting caught off guard by a spike.

It sounds crazy but it worked for me. I had a problem where I believe I was dosing right up to the point of precipitation and wasn't noticing any on my pumps , or anywhere else in the tank. And while my Alk was remaining around 7.5, I was wanting to bring it up to around 9 because I had added a few Acro's to the tank. So I increased the dosage and nothing happened. So I added more and the Alk dropped to around 7.2 about 12 hours later. So I increased the dosage again and it dropped to 7.0. Same thing once again and it dropped to around 6.7. I thought my test kit was bad so I bought another kit and got the same readings. I kept asking everyone and they would say "keep adding more till it stabilizes." I thought I might have a bad batch of Soda ash so I called BRS to see if that was possible. They said when you are getting large swing in the Alkalinity it is usually from overdosing. And that you can disturb the ionic balance of the water to where it can't hold anymore. I believe that was the reason for doing the large water change and letting it sit for a couple of days. And that the large water change would add enough Alk to last for a couple of days while I measure the drop. I was afraid to stop dosing for two days but had run out of options. And sure enough it worked. I started out at 10 ml's and worked my way up, and in about 5 days I figured out my consumption rate. It was lower that what I was initially dosing.

Not saying that that is your problem though. I would listen to Randy and consider his advice to be the most reliable. But if you get to the point where your dosing so much(and getting large swing) that you know it is just not possible, then maybe consider trying something different .

 

[Randy Holmes-Farley]

Randy - Can you expand on the negative feedback loop? In my mind each organism has an optimal uptake rate and anything above or below that would either result in slowed growth and/or recession when taken to either extreme. Also, you are saying a peristaltic pump will 'drift' by dosing at a higher rate per min for the first 2-3 minutes than the next 2-3 minutes (for example) how do you account for this? The motor of the pump?

On the dosing, the tubing in peristaltic pumps can get stretched or deformed, causing the volume delivered to potentially change over time. ALso, two matched pumps do not necessarily deliver at exactly the same rate.

On the negative feedback loop, regardless of whether one might describe it is optimal or not, both abiotic and biological calcification increase as alkalinity is increased and decrease when alkalinity is decreased. That is why dosing is not nearly as exacting as it might otherwise be. Both effects essentially "buffer" against changes in alkalinity. For example, if you take your daily dose that always leads to 8 dKH 24 h later, and deliver an extra 2 dKH with the dose, you will not have exactly 10 dKH 24 h later, but something lower than 10 dKH. It is also why alk rarely drops appreciably below 6 dKH even with no dosing.

 

[AmatuerAuer]

Both abiotic and biological calcification increase as alkalinity is increased and decrease when alkalinity is decreased. That is why dosing is not nearly as exacting as it might otherwise be. Both effects essentially "buffer" against changes in alkalinity. For example, if you take your daily dose that always leads to 8 dKH 24 h later, and deliver an extra 2 dKH with the dose, you will not have exactly 10 dKH 24 h later, but something lower than 10 dKH. It is also why alk rarely drops appreciably below 6 dKH even with no dosing.

If calcification is a function of alkalinity:
1) Can we assume in this context calcification is confined to biological growth and not precipitation.

And if so..
2) Understanding that in your example you are adding 2dkh to get to a perhaps 1.5dkh increase due to buffering and increased uptake - Would that not still be preferable if bullet 1 is true?

In other words, if alkalinity = growth (within reason and with responsible Ca/Mg) should we not strive for higher end alkalinity levels? Say 9.5-10 instead of 8dkh?

I know the answer is no, but don't see the logic.

Thanks RHF.

 

[Randy Holmes-Farley]

If calcification is a function of alkalinity:
1) Can we assume in this context calcification is confined to biological growth and not precipitation.

And if so..
2) Understanding that in your example you are adding 2dkh to get to a perhaps 1.5dkh increase due to buffering and increased uptake - Would that not still be preferable if bullet 1 is true?

In other words, if alkalinity = growth (within reason and with responsible Ca/Mg) should we not strive for higher end alkalinity levels? Say 9.5-10 instead of 8dkh?

I know the answer is no, but don't see the logic.

Thanks RHF.

There are two issues.

Higher alk definitely does lead to higher inorganic precipitation. That's one issue.

Second, at high alk, if the corals are not getting enough nutrition, the skeleton may outgrow the ability of the tissue to keep up, which may be why some corals get burnt tips at high alk in low nutrient systems.

There are chemicals you can add to the water to reduce precipitation (such as polyacrylic acid), but I have not experimented on actual reef systems (just test seawater samples). Driving the alk very high will make some corals grow faster. If that is the only goal (such as for a coral farmer), it is likely worth experimenting with, even if coral color is not optimal due to the higher nutrients driving higher zoox levels.

 

[AmatuerAuer]

Thanks Randy, I have played with the Red Sea A/B mixture and Coral Colors program for the past few weeks. Not sure I will make it a mainstay of my reef but it should help with the nutrition issue (at least in part!).

Thanks again all, more to come as the solution is found!

 

[Randy Holmes-Farley]

You're welcome.

Happy Reefing.

 

[AmatuerAuer]

Following up here, it has been 1 week and my Alk as stayed steady at 8 (+ - .1). I have seen some precipitation on the glass, very faint and easily wiped with my glass cleaner. All the coral (SPS/LPS) have good polyp extension, so I guess stability trumps all so long as it is within the 7-11 dkh range.

Question: If I keep the dosing schedule consistent, at a certain point the increased demand from the coral will catch up and cause the Alk to drop correct (rhetorical)? So my plan is to keep it steady, wait for that tipping point to occur, and then gradually raise the dkh to the desired level of 9. Similar to what Kenmx was saying above, just a different way of achieving the same goal.

 

[Randy Holmes-Farley]

Yes, just occasionally monitor alk to see if you need to increase the daily dose.

 

[AmatuerAuer]

Alk was at 7.7 on the 4th, so I dosed 160ml Alk from my BRS 2 part. Measured today and it was 7.2

My Apex recorded a pH spike at the time of the dose but then immediately returned to the same level as before.. I upped my hourly dosing of Ca and Alk from 5min/hour to 7min/hour (40% increase) Will measure tomorrow and see what we get.

 

[AmatuerAuer]

Upped the dose to 10mins every hour, off set by 30mins for Ca/Alk.

Alk rose to 7.6 on 12/10 then 8.5 on 12/12 then 8.2 on 12/13

Tested Ca and it was 415 on 12/13 and Mg was 1220 on 12/13

I dosed some additional Mg to raise levels to 1350. Will retest today and see where app levels are.

 

[AmatuerAuer]

And now back to 7.6, which means I had a roughly 1 day bounce when I upped my levels.

So...solutions... What about the previously mentioned method:
1) Stop ALL dosing
2) Wait 24hours
3) Test Ca, Alk & Mg
4) Dose to bring them to desired levels (450, 9.5 & 1300ish respectively)
5) Test again to verify that the desired levels were in fact hit
6) Measure the uptake from the tank over time
7) Re-dial in the dosing starting from the bottom up

That should allow me to zero the system so to speak and then raise Ca and Alk slowly together which elevated Mg. ..I mean 9.5 should be a doable thing, right?

 

[Randy Holmes-Farley]

I'd keep dosing as is. There's no big reason that you need to be at higher alk.

I'd suggest seeing where the current dosing stabilizes before jiggering again.