Alkalinity demand when upgrading.

JCTReefer · Apr 27, 2020

#reefsquad
I currently have a 54 gallon reef. Daily consumption of ask is .5 dkh per day.
I dose 20ml a day of BRS two part. I’m upgrading to a 210 gallon. So my question is, when I transfer corals to the new tank, will my daily alk demand be the same? Seems like with a larger water volume, and more alk/calcium/magnesium by water volume, it would be less. Or am I thinking about things wrong here? I mean the corals and other calcifying things will demand that .5 dkh, but there will be more available, with a greater water volume? Increasing alk by .5 dkh in 240 gallons would be 85.7 ml... I’m just kind of guessing that would be my water volume including sump, rock displacement, etc. I won’t know the true gallons until it’s set up.
Just curious on people’s experiences, when they’ve upgraded on alk demand.

Spare time · Apr 27, 2020

I would think you still dose the same amount as before since that is the amount of supplement they needed and water volume doesn't change how much they use. Just try 20ml a day in the new tank and see how it goes.

saltyhog · Apr 27, 2020

I would think if you are dosing 20ml/day now the same corals (if they are growing at the same rate) will still consume the equivalent of your 20ml/day of 2 part alkalinity. For that reason I think of my alkalinity consumption in terms of how much I have to dose to maintain stability rather than dKh change. The dKh change is valuable for relative measurement of each tank but I can compare my tanks when going by how much 2 part each uses.

Edit....I would also bet your consumption of alkalinity by the corals themselves will decrease with the stress of transfer for a while. However, other consumption (abiotic precipitation) may more than make up for that. Check it pretty often for a while.

JCTReefer · Apr 28, 2020

saltyhog said:
I would think if you are dosing 20ml/day now the same corals (if they are growing at the same rate) will still consume the equivalent of your 20ml/day of 2 part alkalinity. For that reason I think of my alkalinity consumption in terms of how much I have to dose to maintain stability rather than dKh change. The dKh change is valuable for relative measurement of each tank but I can compare my tanks when going by how much 2 part each uses.

Edit....I would also bet your consumption of alkalinity by the corals themselves will decrease with the stress of transfer for a while. However, other consumption (abiotic precipitation) may more than make up for that. Check it pretty often for a while.

Gotcha! I’m gonna have to think about this for a while. I’ll just have to do some experimenting when the new tank is set up. Get my target dose. Wait a few days and test every day to see how much its dropping. Rinse and repeat until I get a rough idea of my daily average. My alk fluctuates between 7.9 to 8.4 depending on the time of day or night in my current tank. Thanks for your help. I just couldn’t figure out if I’d need to dose more in a larger tank based on water volume. I’m still scratching my head. Time will tell!

ISFNick · Apr 28, 2020

Spare time said:
I would think you still dose the same amount as before since that is the amount of supplement they needed and water volume doesn't change how much they use. Just try 20ml a day in the new tank and see how it goes.

+1 on that

JCTReefer · Apr 28, 2020

AyeNick said:
+1 on that

That actually does make sense. 20ml’s is 20ml’s. Any way you look at it, no matter what the gallons. If I did dose 20ml’s in a 240 that would be about .12 dkh ... Keeping around the same dose would be great with me. Less money on two part! Not that it’s expensive.

kevin_e · Apr 28, 2020

I wouldn't dose for a little while, personally. I would monitor alk over a few weeks. You may halt or slow growth temporarily by relocating the coral and as a result, spike alk, whixh wouldn't end well.

Auquanut · Apr 28, 2020

saltyhog said:
I would think if you are dosing 20ml/day now the same corals (if they are growing at the same rate) will still consume the equivalent of your 20ml/day of 2 part alkalinity. For that reason I think of my alkalinity consumption in terms of how much I have to dose to maintain stability rather than dKh change. The dKh change is valuable for relative measurement of each tank but I can compare my tanks when going by how much 2 part each uses.

Edit....I would also bet your consumption of alkalinity by the corals themselves will decrease with the stress of transfer for a while. However, other consumption (abiotic precipitation) may more than make up for that. Check it pretty often for a while.

^^Yes. This exactly. One other thing to consider is that with the dramatically increased water volume and available alkalinity in the water column, even with comparable consumption (plus or minus), your dKH should decrease much slower. The flip side of that coin is that you will have to add much more than 20 ml to raise it back up by .5 dKH. If that makes any sense.

JCTReefer · Apr 28, 2020

That’s probably not a bad idea! Corals are mainly Softies and Lps, but still probably a good idea to let them adjust for a while before dosing. I’ll just have to play it by ear. I will map out the rock work with my par meter to get them situated accordingly. Actually, I’ll probably re-acclimate everything slowly light wise after the transfer. And not just stick them under the intensity they were in. Then I’ll ramp up slowly.

JCTReefer · Apr 28, 2020

Auquanut said:
^^Yes. This exactly. One other thing to consider is that with the dramatically increased water volume and available alkalinity in the water column, even with comparable consumption (plus or minus), your dKH should decrease much slower. The flip side of that coin is that you will have to add much more than 20 ml to raise it back up by .5 dKH. If that makes any sense.

According to the BRS calculator that’s about 86 ml to raise it by .5 dkh!!! Needles to say, that’s a lot compared to what I’m used to! I was just confused if I would need to dose that much daily for that .5 dkh consumption. And I don’t think that’s the case from what I’m gathering. I get what you’re saying about the increased water volume and the dkh decreasing slower. I’m really anxious to see exactly how it compares to my current tank. Thanks for your input!!!

Randy Holmes-Farley · Apr 28, 2020

JCTReefer said:
I was just confused if I would need to dose that much daily for that .5 dkh consumption. And I don’t think that’s the case from what I’m gathering. I get what you’re saying about the increased water volume and the dkh decreasing slower.

Folks are certainly correct in this.

The alk and calcium demand may change for other reasons (like an irritated coral reducing growth for a bit), but the volume change does not alter the needed supplement to maintain steady parameters, it only changes the dKH drop or rise that the demand and supplementation causes in the tank.

JCTReefer · Apr 28, 2020

Randy Holmes-Farley said:
Folks are certainly correct in this.

The alk and calcium demand may change for other reasons (like an irritated coral reducing growth for a bit), but the volume change does not alter the needed supplement to maintain steady parameters, it only changes the dKH drop or rise that the demand and supplementation causes in the tank.

Thanks for chiming in Randy.

If 20ml’s a day is maintaining my alkalinity now, it should be roughly the same after moving to the larger tank. And I can’t expect the same .5 drop per day because of the extra water volume having more Sodium Carbonate available etc. Okay, I think I’m getting it right in my head now!