Alk keeps going lower the more I dose

See Gee Sea · May 7, 2020

I checked my parameters before and after a water change and my Alk was low and continues to get lower even after dosing daily. Could I possibly be over dosing it? I only have a few soft corals with some fish in a 91g system:
Parameters (everything tested with Red Sea but Nitrates):
PH 8.2
Alk - 6 dKH dropping to 4 dKH this morning
CA - 440
Mag - 1350
Nitrates - < .25 PPM

lapin · May 7, 2020

Sounds like a testing error or does it do this every water change? It would be hard to lose that much alk without SPS using it up?
You might check your salinity.
What salt mix are you using?
Whats the alk of new mixed water?
How big a water change?
Oh and what are you dosing?

aherre07 · May 7, 2020

It could be precipitating out. Have you noticed an increase in white buildup around pumps and heaters?

Randy Holmes-Farley · May 7, 2020

4 dKH is shockingly low. reef tank water does not usually get that low.

Any chance you are reading the titration backwards? The more you add to the color endpoint, the higher the alkalinity is.

See Gee Sea · May 7, 2020

This is where it’s been consistently changing from blue to green and before the water change it was within the range of 10-11dKH. I’m using Red Sea Pro salt with RODI. I’m supposed to read where the plunger is, right? When I draw I’m usually around .8ml which compensates for the needle right? Thanks! I’m losing my mind here!

Uncle99 · May 7, 2020

The bottom plunger must be on 1ml to start
When I pull to 1ml line I have .9ml liquid.
Your using Red Sea Pro and getting 6 dkh?
Either worst RS batch ever, the salt in the container has settled and needs tumbling, or most likely, testing error.

Randy Holmes-Farley · May 7, 2020

I’ve never used that kit, but ALL syringes are read at the end of the plunger, not ever at the liquid line. That reading is about 0.58 mL Of fluid remaining in the device.

aherre07 · May 7, 2020

Never used that test kit but on the Salifert you're supposed to draw the fluid until the plunger/stopper hits the 1.0 mark. Then when titration is reached the color you're supposed to read where the plunger/stopper is.

See Gee Sea · May 7, 2020

It is and the fluid is around .85 ml. My salinity is 1.025. I have some carbon in the sump. Could that be doing it? I know it lowers Mg but like I said that’s normal.

lapin · May 7, 2020

See Gee Sea said:
......before the water change it was within the range of 10-11dKH.

So you are saying the water change dropped it from around 10dkh -11dkh to around 6dkh ?

See Gee Sea · May 7, 2020

lapin said:
So you are saying the water change dropped it from around 10dkh -11dkh to around 6dkh ?

I checked it an hour after doing the water change On Saturday and it was 11.0 dKH. Checking it today is when these problems started. Could the Seachem Reef Builder gone bad? I’m mixing my BRS 2 part as we speak.

Randy Holmes-Farley · May 7, 2020

See Gee Sea said:
I checked it an hour after doing the water change On Saturday and it was 11.0 dKH. Checking it today is when these problems started. Could the Seachem Reef Builder gone bad? I’m mixing my BRS 2 part as we speak.

No on Reefbuilder going bad. No on carbon causing an issue.

See Gee Sea · May 7, 2020

Okay I'm an idiot! I had the wrong amount of tank water in the test vile! DOH! For some reason I was going off of the CA test of 5ml and not 10ml for Alk! Sorry to have wasted everybody's time. I still happen to be in touch with my high school chemistry teacher. I'll have her yell at me!