Alk drop

[bikerjoe2484]

My alkalinity has stayed super stable for the last 10 days same with my calcium and magnesium only raising a couple parts a day. I tested my water again today. My alk was at 7.3 from 7.9 and my calcium and magnesium are testing within just a couple points of what they were for the last several days my calcium is at 390 and my magnesium is at 1335 does anybody know why my dropped .6 today

 

[Reef.]

My alkalinity has stayed super stable for the last 10 days same with my calcium and magnesium only raising a couple parts a day. I tested my water again today. My alk was at 7.3 from 7.9 and my calcium and magnesium are testing within just a couple points of what they were for the last several days my calcium is at 390 and my magnesium is at 1335 does anybody know why my dropped .6 today

That is not a huge drop…what test kit do you use, did you time the test at the same time, have you removed or added anything to the tank recently?

 

[bikerjoe2484]

I use a hanna checker and I try to test everything about an hour before my lights turn out every day

 

[Sam7]

that very little over 10 day period. If i read that right. If it dropped that amount over 10 days either is the plus or minus error built into hanna testor or your coral used alittle bit of alk and you need to add back in by dosing it

 

[Reef.]

I use a hanna checker and I try to test everything about an hour before my lights turn out every day

That is not a huge drop, its to be expected especially if you are not replacing alk with dosing etc, a 0.6 drop over 10 days is not a concern generally.

 

[bikerjoe2484]

Sorry, no it dropped the .6 today

 

[bikerjoe2484]

that very little over 10 day period. If i read that right. If it dropped that amount over 10 days either is the plus or minus error built into hanna testor or your coral used alittle bit of alk and you need to add back in by dosing it

It dropped .6 today and it has been stable for the last 10

 

[Sam7]

then it just dropped or you tested it different or plus. minus error rate of hanna

 

[Sam7]

see what it says tomorrow.....it will go up and down based on last dosing

 

[Sam7]

i believe the error rate is plus minus .4 or .5 hobby grade testors not super accurate

 

[Reef.]

It dropped .6 today and it has been stable for the last 10

The hanna reagent maybe the issue, I don’t know if you know but some people have issues with it as it ages, and the bottle holds 30ml but you are meant to only carry out 25 tests, not using the last 5ml…sounds more like a testing error more than an issue with the tank.
Worth buying a salifert test kit too, very cheap but an excellent kit, for situations like these its worth double checking with a different test kit

 

[Sam7]

plus your still fine with that alk number A bit low for me but we all go with different numbers

 

[Sam7]

i tend to just test it once a week same day every week and go from there

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, while I'm not suggesting the alk actually dropped 0.6 dKH in a day, as opposed to test variation, many tanks lose substantially more than that each day.

 

[kharn101]

Hello All,
How do people deal with it when you add a new GFO to the tank?
I recently added new GFO into my reactor, and my Alk went from 8.6 to 7.7.
Phosphates dropped from 0.30 -> 0.18 over the course of a few days.

Do I dose to counteract the alk drop? Lets say i know 50 ml will help rebound the Alk fro 7.7 to 8.6?

Or do I wait for the alk to drop, then correct slowly?

Have SPS, so sensitivity is quite important.

Thanks!

 

[Randy Holmes-Farley Verified Community Expert]

If I experienced a drop below my target alk I would dose calcium and alk to replace it. :)

 

[kharn101]

Hello Randy,
So let it drop? Or replace that with the necessary dosage to counteract the drop? Lost a few SPS with the drop, so trying to understand this

 

[Randy Holmes-Farley Verified Community Expert]

With no corals, I might let it drop and see where it stabilizes.

 

[kharn101]

Yea, that’s the issue, have a bit of coral.
Any others large users of gfo have a thought on the matter? I can’t be the only one they needs to recharge a large amount once a month. I am also trying an algae scrubber and hope there is mimimal gfo usage along with the elimination of carbon dosing. I am sitting with 0.18 right now which isn’t too bad, however trying to go towards 0.10 as the upper limit.

 

[Randy Holmes-Farley Verified Community Expert]

Other factors that accelerate precipitation that the gfo
May help induce are high alk, high pH, low phosphate and
Low organics.

Are you doing anything to boost pH?