Why the alk roller coaster in my new system?

[reefkeeper2]

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. 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. And boy is it ugly. 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. After a week of stability the alk is now climbing daily and I've had to reduce the dosing. I'm down to 600ml with the alk still climbing. What gives? Why the roller coaster? All the coral look fine even the few sps frags I have. Could the new rock and sand just sucked up the alk and now it's hit some kind of equilibrium?

 

[chadfish]

Are you testing the alk at the same time of day each time? Do you dose all at once or is it spread out throughout the day?

 

[reefkeeper2]

Same time via Trident. Dosed in equal amounts throughout the day by neptune dos

 

[luu78]

I spread my fully saturated Kalkwasser dosage out from 6pm through morning hours before my lights come on at 1pm with heaviest dosage in the night time when lights are completely off. This definitely stabilize my pH at 8.3 using a Milkwaukee pH meter that I calibrate from time to time. As for my alk, I adjust my Kalwasser dosage amount to maintain the alk level I like. The rest of top off is maintained by my RODI. This way I can tune precisely what I want for alk level but I care more now for my pH to be stable more. Not sure if this helps.

 

[reefkeeper2]

I do something similar but the kalk is not enough to keep the alk up by itself. I have to dose or use the calcium reactor.

 

[Aros]

So a few more details would help. How much water was in the holding tank and how much water is in the new tank? Did you add all the water from the holding tank? Was the new water you added to top off the new tank at the alk range of your holding tank? what is your target alk?

If you add a bunch of new saltwater that had low alk it would lower your readings. If youre dosing a bunch everyday to bring it up and now youre finding that its rising too high, that means youve finally added enough to raise up all that new water. Now you just need to figure out how much your corals are taking up to maintain your target alk number.

 

[reefkeeper2]

New tank with sump volume about 500 gal. Holding tanks with sump not half that. New salt water parameters were matched with the old with an alk of about 8.6, so that is not were the issue lies. Although the sump is filled with old live rock, the display is filled with all new sand and dry rock. It must have something to do with that.

 

[PSU4ME]

I’d suspect the new material in the DT to be the culprit

 

[Joe Rice]

When I started my tank 6 years ago with dry rock and dry aragonite sand, it too was consuming far more alk and calc than seemed right to me. A few months after starting the tank I discovered that most of the sand bed had fused together and was as hard as solid rock. I've always suspected that that's where the alk and calc were going - into some kind of chemical reaction with the sand.

So watch out for your sand fusing; it's a real PITA to have it all fused and practically glued to the bottom glass. Oh, and it seemed to be worse the closer the sand was to any rockwork that was touching it.

 

[highfive52]

Your alk is precipitating out, 800 ml. Holy smokes or mag super low. Dong should chime in.

 

[PSU4ME]

What’s your magnesium at Paul?

 

[reefkeeper2]

Mag is ok at 1488

 

[reefkeeper2]

When I started my tank 6 years ago with dry rock and dry aragonite sand, it too was consuming far more alk and calc than seemed right to me. A few months after starting the tank I discovered that most of the sand bed had fused together and was as hard as solid rock. I've always suspected that that's where the alk and calc were going - into some kind of chemical reaction with the sand.

So watch out for your sand fusing; it's a real PITA to have it all fused and practically glued to the bottom glass. Oh, and it seemed to be worse the closer the sand was to any rockwork that was touching it.

I had this happen myself years ago but I was dosing soda ash instead of baking soda at the time. Never had the problem again once I stopped.

 

[Chris A.]

Have you tested your Po4? My consumption changes once it gets too low. Your sand might be sucking up the Po4 until it balances out and starving your tank.

 

[SteveDola]

Its gotta be the rock and sand. I remember RHF stating it can take 6-8 mths for stabilization to occur for those parameters especially in larger thanks.

What type of rock did you use?

 

[SteveDola]

I believe RHF advise was to stop dosing for a week and let the rock such up what it can then start dosing again...not sure how that would do for corals currently in the tank tho.

 

[MikeG]

I assume you have but have you verified your Trident results with another test?

 

[reefkeeper2]

I assume you have but have you verified your Trident results with another test?

Yup

 

[reefkeeper2]

The demand continues to fall. Down to 450ml a day, almost half of what I was dosing. Whatever the cause it seems to be returning to normal.