Where's my DKH going?

[Rhodesholar]

Hello all.

Ok.

I have a 70 total gallons with 100lbs of live rock and (1) coral frag.

I tested Alk first thing in the morning while the moonlights were still on and ALK was 8.9...perfect.

I tested at 3pm after the halides were on for 3 hours and Alk was 8.3.

Is it normal to lose that much Alk in that short of period with virtually nothing in the tank?

I mean there is some coralline but it's not taking over the tank.

To rephrase.

Is it normal to drop 1dkh per day in tank that pretty much just has some coralline and one frag?

Doesn't seem right to me.

Parameters:

Mag - 1380
Calcium - 390
ALK - 8.3
Phos - 0.03
Temp - 81

Thank you for any response

 

[bertoni]

My soft coral tanks would consume 2-3 dKH in a day due to coralline growth. 1 dKH seems credible to me.

 

[Rhodesholar]

Hello Bertoni.

Thanks so much for the reply.

So that sounds legit?

I totally believe you then because I know who you are and what you know.

Ok. I am going to set my doser to make up 1dkh.

Thanks so much!

 

[bertoni]

I think that consumption rate is reasonable. It's hard to be sure, but you could watch for signs of abiotic precipitation if you're worried. That'd be whitish or tannish deposits on heaters or tank surfaces.

 

[Rhodesholar]

Been checking and testing like a madman.

No abiotic precipitation on the heater etc.

My numbers are accurate. It sure looks like 1dkh per day according to my Hanna Alk checker.

I check and test at the same times everyday. 8am and 5pm and unless I am missing something (and I don't think I am) it look really close to 1dkh of depletion in that time frame.

So basically I test at 8am and get that number and then test at 5pm after the lights are on and get that number. I am not dropping 1DKH from 8am to 5pm but rather 1DKH in roughly a 24 hour period.

Can anyone else chime in and confirm they have that level of DKH depletion in that time frame with a very lightly stocked tank and just coralline?

Thank you to anyone commenting.

 

[Timfish]

HCO3- aka alkalinity aka DIC (Dissolved Inorganic Carbon) is used for photosynthesis by algae too. One of the potential probelms with excess nitrogen is algae can create a shortage in a system. See this paper for more info.

 

[bertoni]

Algae will consume the carbon dioxide part of the bicarbonate ion, but they will release the alkalinity back into the system, for a net zero effect.

 

[Rhodesholar]

I brought up this topic because I had a major screw up and did not want to repeat it.

I killed several Acropora because I raised DKH way to rapidly. It was not my fault it was a bad test kit. The more I added the lower it registered.

I feel terrible but it wasn't my fault.

So anyone just learning to keep SPS learn from my folly. DO NOT RAISE ALKALINITY RAPIDLY IN AN SPS TANK!!!

I got a doser, a good test kit and I am now maintaining 9DKH my Acropora are doing well.

I just wanted to make sure 1DKH of depletion was normal so I didn't overdose again.

I only make the same mistake once.

 

[mpderksen]

Dude, you have too many strings on your Bass! (I'm a low-end guy in a cover band).
Why do you suspect the Alk shift was your SPS issue? I'm probably a little aggressive when I add 2-part. I add Alk hourly via a pump, then ever few days I test and get it perfect. But if I miss the mid-week test, I may read 8, and have to make up a full point. Always just dropped the 50-60ml into the sump.

Michael

 

[Rhodesholar]

Hello Michael.

Hahaha....that was a good one. I play bass also but nowhere near like I play guitar.

So here is what happened.

I had a bad test kit. I kept adding Alk and my test kept telling me the Alk was going down not up. Well my DKH must have gone from like 7 to 15. I was trusting the test kit and thinking maybe the calculator I was using was off. Not the case.

All my SPS were dead in about 24 hours. Fortunately there were no large established colonies only small frags so a lesson learned.

I never want to make that mistake again so I posted out here how fast or slow to go raising DKH. I know the slower the better but I didn't want to take a week to do something that could be done faster safely, so I posted out here to get the general consensus.

Thanks for your reply.

 

[mpderksen]

Right, so 7 to 15 sounds like when I added what I THOUGHT was a gallon of RO, and it was concentrated Mg!!! Yep, lost half my tank. Been there.

Of COURSE <1 DKH/day is best, but I can tell you that IME raising a full point on occasion hasn't hurt me. Wouldn't make it a habit, but I do tend to under shoot with my dosing pumps and then make up the different on my weekend testing. I'm getting closer and closer each week.

Michael