Alk calcuator off????

[Michael Gray]

I bought the bulk red kit that Comes with gallon jugs ca alk mg. Alk is soda ash. I mixes it per directions.

My tank is waterbox 130.4. With 12tlbs rock and around 60lbs sand. When. I filled tank I figured roughly 119 gallons if water.

Tank has 6 fish. No corals yet. But ordered some lps.

Mg is 1500
Ca is 440
Alk 8.2

My alk was 7.0. I went on brs calculator and it said about 180ml to raise from 7 to 9. 9 is where I want it. I did this over 48 hours even though I have no coral.

I tested tonight because some LPs are coming tomorrow morning. Alk is 8.2. I tested twice with my hanna. Why is the calculator so off??

I went back to calculator and put in 212g tank 7 to 8.2 dkh is 180ml. Im confused.

I just dosed another 30ml. I'll test tomorrow morning to get idea what 30ml raises my tank from 8.2dkh

 

[Michael Gray]

Not sure why I cant edit this. But I figured tank has 110g of water not 119.

I did the calculator attached photo. Dosed the 160 over 2 days and it only went to 8.2dkh instead of the 9dkh.

I went into the calculator and changed it to 7 to 8.2 like it is currently and for for same amount I dosed. It is reading 184gallons of water.

 

[andyg1960]

I’ve never known the calculator to be “off”. Possible options:
Mixing error
Testing error
Water volume error
Something consuming Alk

 

[Michael Gray]

I’ve never known the calculator to be “off”. Possible options:
Mixing error
Testing error
Water volume error
Something consuming Alk

could be mixing error but no way i can be mixing it half potency. but never say never.

im wondering what can be consuming alk. no coral. just 6 fish. i have been feeding heavy last 3 days because im trying to get nitrates to 10ppm for LPS.

ill test when i get home from work at 8am. i dosed 30ml last night so ill see the jump and write it down. and dose same amount and see if it goes up equal amount.

 

[crawling junk]

Or your hanna test kit reagent is off. Which is a known issue. A batch of reagents was off by 1dkh

 

[Michael Gray]

Or your hanna test kit reagent is off. Which is a known issue. A batch of reagents was off by 1dkh

Oh how do I find out if I have a bad one. I'll test with my red sea this morning as well and compare

 

[crawling junk]

Yes test with another kit. Also there is a thread on hanna section in this forum

 

[Michael Gray]

Thanks. I'll look into it.

 

[Bulk Reef Supply]

I’ve never known the calculator to be “off”. Possible options:
Mixing error
Testing error
Water volume error
Something consuming Alk

Nothing about the calculator has changed, so one of these possibilities are likely the case. I'll also add that if you're adding it too quickly, you could get precipitation (which would lead to lower than expected alk levels). The Hanna checker also has a margin of error of 0.3 dKH, so that could contribute too.

 

[randyBRS]

Hey there,

Just looking into this a bit deeper, is there a reason you are changing the water volume from one calculation to the next?

I'd agree in your guess that the tank's total water volume (minus displacement for rocks and sand) is around 100-110gal total. That said, the total water volume shouldn't change when calculating a raise in dKH.

If you tested your tank at 8.2dKH after 48hrs, but you still wanted to be at 9dKH, then the calculator should look like the one below. (Water volume is still 110gal. You're current Alk level is now 8.2dKH, you want to raise it to 9dKH.)

There is some expected margin for the calculation which can come from a variety of factors specific to each individual's tank.
1) The volume is always a hard one to get 100% correct on any system and anyone's guess is pretty much a ballpark that could be off by +/-10gal or more.
2) Also, it could reasonably be expected that the alkalinity has some degree of daily "fall/drop" even without corals which can skew the end Alk result.
3)Along with that are the resolution ranges for the Hanna Alk checker which has an accuracy window of +/- 0.3dKH which means your 8.2dKH could actually be 7.9-8.5dKH.

In the end, corals are very resilient creatures in that they can live/thrive in a wide variety of water parameter ranges. So whether you run your tank at 7.0-11.0dKH, I don't doubt that they will be just fine. The biggest key here is going to be stability where you do your best to keep all your water parameters as stable as possible (salinity, alk, cal, mg, nitrate, phosphate, lighting, flow, etc.) to give your corals the best chance at living and thriving for years to come!