Why the alk roller coaster in my new system.

[reefkeeper2]

I just completed my new 400 gal build. After placing all my critters into their new home from their holding tanks in the basement, the alk levels in the new system started to quickly fall. I couldn't figure out why because it's just the same number of coral in a larger water volume. The rock in the display is all new dry rock. The old live rock from my prior tank is in the sump. I'm not presently using my calcium reactor, choosing to dose until I have a larger population of coral. This helps keep the pH up and phosphates down during the ugly phase my tank is going through. Anyway, over the course of the next week I was dosing up to 800ml of alk a day in addition to all the top off coming out of the kalk reactor. Previously the kalk reactor handled the demand all by itself. After a week of stability the alk is now climbing daily and I've had to reverse course and reduce the dosing. I'm down to 600ml and the alk is still climbing. What gives? Why the roller coaster? All the coral look fine even the few sps frags I have. Can't figure out what's going on.

 

[Jekyl]

Not an expert on the subject but I know the nitrification cycle will consume alk. New rocks and new growth will suck some up.

 

[\m/reefsnmetal\m/]

Are you by chance using a Hannah alk checker? It could be testing error. I've read a few threads on here with people getting weird readings, including myself. My alk was increasing despite the lack of dosing.

 

[HuduVudu]

It is because not only is your tank new, so are you. This isn't slight it is an admonation. There are many different chemical issues at play. This is a good time to get in and do some research.

@Jekyl is right the nitrogen cycle consumes alk. Also elevated CO2 both in and out of the aquarium consume alk. There is also interplay between PH that needs to be understood especially when it comes to dosing.

Lots of things to understand here.

Aren't salt water aquariums fun.

EDIT: Ohhh yah and don't forget (because I just did) that you should never fully trust your testing equipment.

 

[reefkeeper2]

I've been keeping reef tanks for 30 years and have had a "tank of the month" back in the good old days on Reef Central. My last tank was featured in Advanced Aquarist. I'm hardly new. I'm sure you were trying to be helpful.
The tank is not cycling, since there is ample live rock in the sump though I'm sure the new rock and sand is under colonization by bacteria which could explain some of it. This is not my first rodeo putting up a new tank and have never seen this happen before in any of my previous builds. Doubt pH has anything to do with it. The pH daily range is a low of 7.93 to a high of 8.13 .

 

[reefkeeper2]

Are you by chance using a Hannah alk checker? It could be testing error. I've read a few threads on here with people getting weird readings, including myself. My alk was increasing despite the lack of dosing.

I have a Trident and a Hanna Alk checker. They match.

 

[Danroo]

More nitrifying bacteria more consumption, it’s a same issue with my tank I barely have any corals, but the consumption of alk is 0.5 every 3rd day. Probably having more rocks causes this issue but I guess having more nitrifying bacteria is better for the tank.

 

[reefkeeper2]

More nitrifying bacteria more consumption, it’s a same issue with my tank I barely have any corals, but the consumption of alk is 0.5 every 3rd day. Probably having more rocks causes this issue but I guess having more nitrifying bacteria is better for the tank.

It sounds like the most likely explanation but like I said I never saw this on any of my previous builds. My last tank was the same size, 400 gal with new sand but with live rock from the previous tank. This tank has live rock from the previous tank in the sump, with a whole new aquascape of dry rock in the display.

 

[Randy Holmes-Farley]

Can you post the actual alk measurements?

 

[reefkeeper2]

Right now the alk is at 9.3, so it has slowly risen over the past week from 8.6 though I have reduced dosage to 600ml a day. I will continue to slowly reduce dosage as long as it keeps climbing.

 

[Randy Holmes-Farley]

Right now the alk is at 9.3, so it has slowly risen over the past week from 8.6 though I have reduced dosage to 600ml a day. I will continue to slowly reduce dosage as long as it keeps climbing.

OK, it's a slow roller coaster.

I'd just try reducing the dose and see if it stabilizes better.