Help with Alkalinity stabilization

TwoFish

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#1
Hi all, let me tell you first about my tank.

Capacity: 110 gal
Sump: Yes
Lighting: 2 Radion XR30 G4 and T5 hybrid
Flow: 2 MP40 & 1 MP10
Refugium: Yes, red macro algae and chaeto (Kessil H380)
Skimmer: Yes (rated 150 gal)
Carbon: Yes (Red Sea brand), changed biweekly
Mechanical filtration: Yes (Polyfilter in media cups), changed twice a week
Salt mix: Tropic Marin Pro
RODI: Yes, 0TDS
Water Changes: Yes, weekly, 10gal
Bioload: 9 reef safe fish (angles, clowns, tangs)
Type of Reef: SPS dominant (90% acros)
Coral count: 36+ acros
Rock: Yes (60 lb)
Sand: No, bare bottom
Dosing: Yes, 2-part Soda Ash & Calcium Chloride (GHL 2.1 doser) and KALK (100mL daily no changes), Discontinued Potassium Nitrate
Tank age: 2+ years
Parameters: Alk-9.9 / Ca:440 / Mg: 1490 / NO3: ~3 / PO4: 0.05 / PAR: ~320 avg
Feeding: Spectra Thera and frozen food (blood worms), Heavy twice a day, Discontinued Oyster Feast
Test Kit: Hanna Alk checker, Salifert Mg, Red Sea Ca, Hanna low range PO4, Nyos NO3
0D88D4C5-F8CB-47BA-9F66-4BCD1BCE0AE4.jpeg


Question: Alk has been stable for the past 6 months at 8.6 dKH and consuming 130mL of equal 2-part per day (+100mL kalk/day). I had a crazy swing of 1.5 dKH rising to ~10dKH when I started dosing Potassium Nitrate to increase nitrate to ~5ppm since it was undetectable 3 months ago. I have since stopped dosing Nitrates and performed a 30gal water change for three days to slowly bring down the Alk level back to 8.6, which it did, and stayed there. A month ago however, I started noticing my Alk was slowly creeping up again ever since I started feeding oyster feast. My response was to decrease the daily dose of 2-part and adjust it accordingly. Fast forward to today, my Alk is at 9.9, and exactly 3 days ago it was at 9.6, a 0.3 dKH increase. What I think is happening is my tank is stabilizing at a higher Alk value. Today my 2-part daily dose is at 120mL For both. I will update on the Alk level after the W/C.
Back to my question; Could my feeding of coral foods or dosing nitrates unwillingly increase alkalinity?
Reasoning: Everything in regards to water chemistry is consistent. Test, use reef calculator, adjust daily dose of 2-part, retest, repeat. Alk was rock solid for a year doing this. It was only until after I started messing with nitrate dosing and feeding oyster feast was when Alk started swinging.

Thanks all for your input.
 

TwoFish

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#3
No. You chasing higher nitrate levels probably resulted in some browning and corals drop in consumption. Its take a couple of weeks to see full effects and things to stabilize
I figured that Nitrate might have affected the corals, such as “browning”, or simply reacted negatively to the sudden change in nutrients. Before pinpointing the exact reason for calcium and alkalinity uptake change, I know that nitrate and phosphate don’t directly affect alkalinity levels at all, rather can affect the corals color and health, which means these levels act as an intermediate between how much is present at one time, and how much alkalinity is read on a test kit based on these nutrient levels. Moving on, when corals are upset, they show this on the alkalinity readings, henceforth reduced calcium consumption as well. Could this be what I am seeing in my tank?
 

TwoFish

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#4
I just noticed something, could my drop in Alk consumption (i.e. higher alk due to less of it being consumed and accumulating) be a result of less coralline algae growth as well?
 

Smite

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#6
Nice tank. 100% agree with joseserrano. You changed a parameter and your consumption dropped and that sent you into a less stable period with your corrections. It'll take a good period of stability for your consumption to return. Adjust your dosing to your current demand and monitor the tank.
If it creeps up in the future I'd suggest adjusting the doser over pulling the numbers down with water changes.
 

TwoFish

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#7
Thanks, the tank is stable at 9.7 dKH now. I’m not too concerned about the number, but as long as it’s stable and things are growing. In the future, how would I go about increasing nutrients to the tank slowly as I move to the next stage of reefing, from frags to colonies? I’m not sure what to expect to do differently because this is my first success with acros growing super fast and coloring up nicely.
 

Smite

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Thanks, the tank is stable at 9.7 dKH now. I’m not too concerned about the number, but as long as it’s stable and things are growing. In the future, how would I go about increasing nutrients to the tank slowly as I move to the next stage of reefing, from frags to colonies? I’m not sure what to expect to do differently because this is my first success with acros growing super fast and coloring up nicely.
That's the answer to your question right there, if it's not broken don't try and fix it :)

If you're feeding 2x a day and doing oyster feast a few times a week (if you start again just start @ 1/2 the recommended dose) I wouldn't worry about raising your nutrients, your corals are being well fed. You have detectable nutrients so you're golden.

Be as stable as possible for a few months, then if you're not seeing the color ect you want manipulate one thing at a time, flow/lighting/aminos/nutrients/, then monitor the tank.

It's easier said than done, I'm horrible at changing too much at once but that's my current goal.
 

joseserrano

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#10
Thanks, the tank is stable at 9.7 dKH now. I’m not too concerned about the number, but as long as it’s stable and things are growing. In the future, how would I go about increasing nutrients to the tank slowly as I move to the next stage of reefing, from frags to colonies? I’m not sure what to expect to do differently because this is my first success with acros growing super fast and coloring up nicely.
Yes. Truly understand why you are doing something before you are doing it. The nutrient high systems seems to just be the new trend.
 

TwoFish

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#11
I’m not really concerned with the trends, but more so bringing out the best possible colors. However, I’m mostly concerned with how system stability changes as a reef tank matures. This will help me prepare for what is to come in the future. Once again thanks for your input
 
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#12
I think Jose is probably right on here, but I wanted to throw in here to make sure your dosing pump is still calibrated correctly. If it is tossing in more solution than that will raise your alk. I am not familiar with the exact products you are dosing, I am more of a brightwell guy, but in the past I did use a 2 part that varied a bit batch to batch. Each time I got new bottles from the store, I would have to recalibrate my dosing to maintain a consistent alk.

FWIW I have found dosing small amounts of amino acids have been the best way for me to have a consistent level of both nitrate and phosphate for my tanks. I feed the fish 4 times a day with feeders but also have aminos on a dosing pump just before lights out. I kick the skimmer off for an hour at the same time. If you are looking to increase color, I highly recommend that. Of all of the things I dump in and test for in my tank, and I have about 7 bottles I supplement now, amino's are the biggest change in color IME.

Good luck with the tank!
 

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