Alk Consumption Expectation - 4mo old 200g Bare Bottom (>330mg/day?)

[135reef]

Struggling to get Alkalinity and Calcium in-balance. Is 330+mg/day CA+Alk reasonable at this stage?

160 Display (200g Total)
100# Dry rock cooked/cycled 3 mo
1/2cf MarinePure 2" cubes in sump
Reef Crystals (10g/week auto-changer)
Dosing BRS Pharma Alk, Ca and Mg
80W UV
Recirculating Skimmer
3M stock tank
3x Filter Socks (Changed every Saturday)
Algae Reactor (No algae yet)
Had small amount of algae on the bare bottom and a couple of rocks, but the Tang resolved that in <24hr
No Coraline yet
Lights have been on 3mo (4 x T5s + 3 x Radion G4)
Par range of 280 to 400
6 SPS frags moved over from previous tank
1 fish in the display. Next round in quarantine
Small number of crabs and snails for early maintenance
pH = 8.1 (when dosing)
Mg = 1369
Salinity at 35 (1.026)
Temp range 77.5-78.0

• I ramped my Alk and Ca to 280mg/day driving to targets of 8.5-9.0(Alk) and 450-475(Ca).
• Checking heaters, I noticed precipitation build up between the cover and titanium heater core.
• With Trident dosing enabled, I still couldn't get the Alk and Ca to maintain my targets and was seeing Alk pushing 330mg/day and Ca at 240mg/day, but the Ca and Alk are not sustainable.
  • Reviewing the BRS video on over-saturation, I turned the Alk and Ca off. Alk went from 8.3 to 8.0 in 12hrs
  • I did a 30g water change and have been monitoring. (Dosing off)

I'm a little lost at this point. Did I over-shoot initially? It feels unreasonable to be dosing 350+mg of Alk with no Coraline and small number of frags at this point. Can the dry rock be consuming this much Alk/Ca at this stage?

What am I overlooking?

Open to suggestions...

 

[laverda]

That does seem high, especially since you ALK only dropped.3 in 12 hours. Are you dosing both simultaneously? If so you would likely get localized participation.

 

[135reef]

Thanks @laverda,

Dosing is offset and I have a Tunze power head blowing directly at the entry point in the sump. pH bottomed out at 7.91 this morning. The support room is isolated from the house so we have ample fresh air supply. Even when dosing 300+mg of Soda Ash per day, we never saw the pH over 8.05.

With Alk and Ca dosing off, Alk continued to dive overnight but Ca improved.

Magnesium is dosing at 60ml/day and remaining pretty steady.

I'm missing something...

Alk crashes (confirmed with Hanna)
CA remains stable
Mg remains stable
pH is low but not horrible when dosing
Automated water change source (RC) Alk is at 9.4

Any other thoughts?

 

[135reef]

More research and new approach.

1 - Doubled water changes to 2g/day (just shy of 10% of display/week)
2 - Leave Ca dosing off and continue to monitor interaction with Alk
3 - Slowly re-start Alk dosing based on BRS calc of 178ml to bring Alk back to 8.6 from 7.35
4 - Leave Mg dosing enabled and monitor (maintain below 1400)

 

[135reef]

Not good progress. I'm still missing something. After dosing 125ml of Alk, the tank is down to 7.29, but the calcium held pretty good at 444 down from 454.

I'm going to kick off another water change and let things sit for 24hrs.