Alk drop after a water change ??

cracker · Feb 19, 2018

Hello, I'm trying to keep my 75 reef as stable as possible. I pay close attention the alk . I want this at 8.0 with Ca around 400/420. So after a water change The alk level drops around a point to the low 7.0's. I take a day to dose it back up to 8.0 .
Ya think this 24 hour drop is too much? Should I dose it up all at once? I'm prepared to dose the makeup water to proper levels before a water change. Any opinions would be appreciated !

Crabs McJones · Feb 19, 2018

Before you put your water in check the alkalinity level of the water your mixing first and see if the alkalinity level is low in your new water. If you're mixing to the same alk it shouldn't be dropping. What salt mix are you using?

cracker · Feb 19, 2018

I'm using regular Red Sea salt. when I test right after mixing the alk is higher/close to where I want it. However I can't always do the water change right away & it may sit in the barrel for a day or two. The Alk is lower after a couple of days. Now I'm prepared to dose up the new water but wouldn't mind not having to ! Is this 1 point drop, say from 8 to 7 then back to 8 in a 24 hour period going to tick off my corals?

Crabs McJones · Feb 19, 2018

cracker said:
I'm using regular Red Sea salt. when I test right after mixing the alk is higher/close to where I want it. However I can't always do the water change right away & it may sit in the barrel for a day or two. The Alk is lower after a couple of days. Now I'm prepared to dose up the new water but wouldn't mind not having to ! Is this 1 point drop, say from 8 to 7 then back to 8 in a 24 hour period going to **** off my corals?

It might, anything more then .5 per day may upset them from what I've been told.

cracker · Feb 19, 2018

That's what I hear also. That is my goal, .05 changes no more. Thanks !

cracker · Feb 20, 2018

How big of a deal,(just checked my log) is a drop from 8.0 to 7.1 every 2 weeks or so? I have it back to 8.0 in under 24 hours. Also I'm doing 25 gl water changes in a 90 gal system. Think I should not change that much water ? Like Crabs says" it might" . Any other Op's?
Thanks !

Randy Holmes-Farley · Feb 21, 2018

cracker said:
How big of a deal,(just checked my log) is a drop from 8.0 to 7.1 every 2 weeks or so? I have it back to 8.0 in under 24 hours. Also I'm doing 25 gl water changes in a 90 gal system. Think I should not change that much water ? Like Crabs says" it might" . Any other Op's?
Thanks !

That's a slow alk drop, but I'd dose a couple of times over (if not daily) that period to maintain alkalinity.

cracker · Feb 21, 2018

Thank You sir !

saltyfilmfolks · Feb 21, 2018

A fwiw, just wc and slow increases and decreases won’t harm you really at all. Ime.
The alk stability craze IMO is a bit overblown. Plenty of of tanks including mine have done fine without these considerations.
Many running IO or RSCP (higher all salts) just do standard water changes without the testing or concern of “spike “ and stability, dosing or no.

If the uptake was large yes, I’d be concerned perhaps. Then matching salts parameters to the tank may become more of an issue.
But in the last year I’ve used IO and also NSW, (13/7.5 respectively), and the only thing I’ve observed is the minor adjustments to the doser.
Not to the coral.

It’s only been in cases of extreme low alk I’ve had issues , and not with growth rate , the skeltons are just soft. Mostly noted in montiporia being soft and brittle.

Potatohead · Feb 21, 2018

If your alk is 8, you could do a 10% water change with water with zero alkalinity and your alk wouldn't end up at 7, so I suspect a possible testing issue.

cracker · Feb 28, 2018

So I just tested a fresh ,just mixed barrel of Red Sea salt. Got a DKH 7.0 with a Hanna checker. Now water temp was a little low 74 degrees . I'm going to wait till tomorrow maybe the next & test again. I see I will have to dose up the barrel before using. or I just go with the new water reading. I don't know.
Edit: Thank Salty, So according to Red Sea Alk at 77 degrees will be between 7.8 & 8.2. I got 7.0 That doesn't sound right to me. So ,either the temp wasn't right I got a temp of 74, Or the water wasn't quite all mixed well ,Or salinity wasn't 1.o26 I tested at 1.025. Not a big difference for all scenarios. So 2 hours later, I will test temp, salinity & Dkh again. I did test right after I hit the 1.o25 salinity Maybe too soon. So we shall see.
I do love the challenge !

cracker · Mar 2, 2018

I ended up dosing 10 mls Of Prt 2 (alk).. brought it up to 7.8 which is where the tank is now. So If I have to add 10 mls before doing a water change ,no big deal at all ! Also everybody looked lousy right before the w/T next morn everybody was happy ?? It had been only 2 weeks. Makes me wonder.

Randy Holmes-Farley · Mar 2, 2018

cracker said:
So I just tested a fresh ,just mixed barrel of Red Sea salt. Got a DKH 7.0 with a Hanna checker. Now water temp was a little low 74 degrees . I'm going to wait till tomorrow maybe the next & test again. I see I will have to dose up the barrel before using. or I just go with the new water reading. I don't know.
Edit: Thank Salty, So according to Red Sea Alk at 77 degrees will be between 7.8 & 8.2. I got 7.0 That doesn't sound right to me. So ,either the temp wasn't right I got a temp of 74, Or the water wasn't quite all mixed well ,Or salinity wasn't 1.o26 I tested at 1.025. Not a big difference for all scenarios. So 2 hours later, I will test temp, salinity & Dkh again. I did test right after I hit the 1.o25 salinity Maybe too soon. So we shall see.
I do love the challenge !

The alkalinity doesn’t change with temperature changes. [emoji3]