Chasing Kh on new tank???

[niccumec]

I almost hate to ask this as I have read several similar threads on this topic, but none seem to answer the simple question for a new tank. Here goes…

On a new tank (~2 months) with no corals (FO with copepods) and low alkalinity, is it advisable to dose to maintain KH or is that possibly just exacerbating the problem of abiotic precipitation?

My KH was very low ~5dkh based on RedSea Pro test. I added baking soda and bumped it to 9dkh, only for it to quickly fall off again. All I can imagine is that a bit is due to Nitrate climbing from 5-10 ppm and abiotic precipitation? My pH “wants” to be ~7.9. I have AWC of 2.2gpd (in a 190 gal system). Using HW-Marine Reef Salt.

Bottom line is that I am okay using Randy’s 2-part dosing recipes, but if I am simply adding more source for precipitation, am I wasting my time dosing at this stage? Should I just let it be for a few months - even at such low alkalinity? Will biology take over to reduce likely precipitation?

All I can imagine that is “using” Alk is:
- slight increase in Nitrate (5-10ppm)
- precipitation (nothing noticed in sand)
- copepods and phyto dosing - do these critters deplete alkalinity???

 

[eliaslikesfish]

Alk is consumed by many biological processes in a tank other than coral. Younger tanks can consume alk at an astonishing rate as their biology gets established.

Just keep the alk up with grocery store baking soda. I wouldn't bother checking more than once a week since you don't have coral. At some point the alk consumption will level off and that's usually when long term tank stability starts.


Also, never hesitate to ask something, we’re all here to help!

 

[niccumec]

I was planning to dose the baked baking soda to raise Alk and pH together since my pH is also low.

 

[eliaslikesfish]

what’s your pH at?

 

[Randy Holmes-Farley]

Maintaining 7 dKH seems easy and appropriate. Coralline may get going faster if alk is not too low.

 

[niccumec]

what’s your pH at?

PH is currently running ~7.8-8.0.

 

[eliaslikesfish]

PH is currently running ~7.8-8.0.

yeah don’t worry about it too much. chasing pH is gonna give you one heck of a headache.

 

[niccumec]

So, just about of curiosity, do the pods also consume Alk and Ca in any appreciable way?

I added 4 strains of benthic pods just after cycle (and dosing phyto 1ml/gal/day) to try to start colonizing in external refugium and DT. They are doing quite well and have totally cleaned the film algae off of the glass.

 

[Randy Holmes-Farley]

So, just about of curiosity, do the pods also consume Alk and Ca in any appreciable way?

I added 4 strains of benthic pods just after cycle (and dosing phyto 1ml/gal/day) to try to start colonizing in external refugium and DT. They are doing quite well and have totally cleaned the film algae off of the glass.

Not, not at all by actual consumption.

Rising nitrate will deplete alk.

 

[niccumec]

Maintaining 7 dKH seems easy and appropriate. Coralline may get going faster if alk is not too low.

Do you recommend doing so with baking soda or baked baking soda. If I just targeted 7-8 dkh, then the baked baking soda would likely get me in the low 8’s in pH versus the upper 7’s for regular baking soda. Both are easy for me to do. Not so much chasing pH, but if I am dosing something anyway…

Also dose Calcium to stay in balance or forget about it until I add corals?

 

[Randy Holmes-Farley]

Do you recommend doing so with baking soda or baked baking soda. If I just targeted 7-8 dkh, then the baked baking soda would likely get me in the low 8’s in pH versus the upper 7’s for regular baking soda. Both are easy for me to do. Not so much chasing pH, but if I am dosing something anyway…

Also dose Calcium to stay in balance or forget about it until I add corals?

It won’t matter much since you won’t be dosing frequently, but the baked would be slightly preferred.

Calcium should still about match your salt mix. Does it?

 

[niccumec]

It won’t matter much since you won’t be dosing frequently, but the baked would be slightly preferred.

Calcium should still about match your salt mix. Does it?

Calcium dropped from 425 to 380 over 10 days on Red Sea Pro test kit.

 

[Randy Holmes-Farley]

Calcium dropped from 425 to 380 over 10 days on Red Sea Pro test kit.

That would likely be a test error issue. The only ways that would happen in your tank are a big salinity drop, or precipitation of calcium carbonate that would have necessarily consumed about 6.6 dKH of alk. If that large of an alk drop didn’t happen, then test error is most likely.

 

[elysics]

Have you measured the water that your AWC system draws from? And yeah salinity of both the tank and that reservoir

 

[niccumec]

Have you measured the water that your AWC system draws from? And yeah salinity of both the tank and that reservoir

Yes, my mix tank (AWC) source mixes relatively low Kh (HW-marine Reef salt), but I add baking soda to bump it to 9 dkh. Both DT and mix tank are right at 1.0252 measured with Tropic Marin hydrometer (and adjusted for temp).

 

[niccumec]

That would likely be a test error issue. The only ways that would happen in your tank are a big salinity drop, or precipitation of calcium carbonate that would have necessarily consumed about 6.6 dKH of alk. If that large of an alk drop didn’t happen, then test error is most likely.

@Randy Holmes-Farley, That dkh drop is not out of the realm of possibility. Not sure how all the math works, but when I started, the DT was <5.3 dkh (lowest reading on Red Sea Pro chart). It took 63 grams of baking soda to raise it to 9 (system volume ~190 gal). Since 6/1/24, I have added an additional 123 grams baking soda over 10 days from 6/1 to 6/11 bumping kh up, until I stopped adding and started asking this question.

Summary:
6/1/24: Raised Alk from <5.3 to 9 dkh (+63g baking soda) | Ca 425 | Mg 1400
(AWC mix water also 9dkh and Ca 425)
6/1-6/11/24: +123g cumulative add of baking soda
6/11/24: 6.3 dkh | Ca 380

This is why I was worried that I could be exacerbating precipitation by adding baking soda. While I do not see any precipitation on rocks or sand, I guess it must be there…. I have had material in my skimmate, but thought it was diatoms or something. Could my skimmer be removing calcium carbonate precipitate as well? I have a high flow rate circulating through the DT and sump ~1600 gph and a strong LifeReef Venturi skimmer (running wet - not a ton of load with only 2 small clowns)