How much should I chase ALK?

James Johnson

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If everything is looking fine I would just stay where you are at.

If you feel like alk is low then I would just bump up your 2 part by a little bit each week and then test again the following week and see where your numbers stabilize at.

IMO other than your alk, your parameters look fine to me.
That’s bad advice his alk needs to be higher than that
 

James Johnson

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Alk at 6.8? That’s barely low. A couple teaspoons of baking soda will fix that. Now, my alk was low....
7c7cfd37-7be1-4fc9-b776-8494e7ac9f06-jpeg.1571484

But Alk is very easy to correct with baking soda.

That’s also bad advice, baking soda is very strong when compared to other alk products it’s very easy to overdose with, go to the store and buy alkalinity in liquid form and follow the directions each alk product has a different concentration, there is a reef calculator on marine depot if you need help
 

Vette67

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That’s bad advice his alk needs to be higher than that
It is actually not that far off from natural sea water, which has an alkalinity of 7.0.

That’s also bad advice, baking soda is very strong when compared to other alk products it’s very easy to overdose with, go to the store and buy alkalinity in liquid form and follow the directions each alk product has a different concentration, there is a reef calculator on marine depot if you need help
it is absolutely not bad advice. Baking soda is sodium bicarbonate. It is no different than the baking soda you get from BRS. If anything BRS sodium bicarbonate might be ever so slightly more pure, which by your argument would make it stronger. As a matter of fact, if it was so bad, why did adding 25 teaspoons of Arm and Hammer correct my alkalinity problem? If you prefer to use liquid alkalinity, that is your choice. Recommending sodium bicarbonate is in no way, shape or form, bad advice. Why would BRS sell bulk baking soda if it was?
 
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Eyedogtor

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Hello,

I have a 190g reef tank that has been up for about 10 months. Everything is looking great (SPS, LPS, Zoas, etc.). I dose aquaforest 3 part, and do continuous water changes through my Apex/DOS pump - about 1 gallon per day. My challenge is that my ALK is low - 6.8. CA is 415, MG is 1400, Phos is 0.03.....not sure how much I should 'chase' this low ALK vs. just observing talk progress as a measurement?

Thanks for any advice - and here is a video of the tank as an example.



Pat

Sorry - here is video without sharing restrictions:

 

fishguy242

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hi ,that reef is consuming a lot of cal& alk ,would slowly bump up cal to 450,alk 7-9 range
very nice btw ;)
 

TMB

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That’s bad advice his alk needs to be higher than that
I’m curious as to why you feel keeping it where it’s at is bad advice. Is ALK @ 7 way off from normal parameters? And if you feel it’s way off, what is the preferred alkalinity level for this tank?


Oh, and @Chaswood79, you better get in here, we got some more “bad advice” going on!o_O
@Sisterlimonpot
 
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Duncan Tse

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That’s bad advice his alk needs to be higher than that

Like the above posters said, why do you think this was bad advice?

Although I agree 6.8 may be a little on the low side, I don't think it's detrimental to his reef tank.

Natural seawater is at 7 dkh and all his corals are doing fine and looking healthy.
 

AD87

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The more middle range you can get the more it can swing without negative consequence. If you raise it to say 8-8.5 it can swing to upper 9s and lower 7s or high 6s without negative effects.
 

Hans-Werner

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Scientific literature (Millero, Chemical Oceanography) gives the normalized (to 35 psu salinity) total alkalinity of natural seawater with 2290 µmol/kg to 2370 µmol/kg with most plots in the graph at 2300 to 2320 µmol/kg. The conversion to dKH is 1000 µmol/l (1 mmol/l) = 2.8 dKH. To be totally correct you have to multiply this with the sg of seawater at 35 psu of 1.0264. The results are: 2.3 * 2.8 * 1.0264 = 6.61; 2.32 * 2.8 * 1.0264 = 6.67;
The results are 6.61 and 6.67 dKH.
The total alkalinity of natural seawater at 35 psu does barely exceed 6.6 dKH anywhere in the world. In the tropics of the Pacific and in the Atlantic it generally is at or slightly above 6.6 dKH.

If the alkalinity tends to stabilize at 6.8 dKH alkalinity with mineral additions I recommend to leave it there. Trying to elevate it by force will stress the corals, cause polyp contraction and slower growth.

Phosphate concentration influences the point where your alkalinity is balanced and quite stable. With higher phosphate concentration alkalinity will stabilize at a higher value. Increasing phosphate concentration to 0.1 ppm will give you higher stable alkalinity, better polyp extension and faster growth of corals.

If corals look good I recommend not to change anything. If you want to change anything, feed more and try to increase phosphate concentration.
 
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Randy Holmes-Farley

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There's no benefit to
That’s also bad advice, baking soda is very strong when compared to other alk products it’s very easy to overdose with, go to the store and buy alkalinity in liquid form and follow the directions each alk product has a different concentration, there is a reef calculator on marine depot if you need help

The way to dose baking soda is to dissolve it in water first. You can make any potency you want that way, up to the a solubility limit.
 

Hans-Werner

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Here is a scientific article about total alkalinity and total normalized alkalinity in the tropical and subtropical surface ocean. You can convert these numbers with the formula I have given above. It is not a mystery.
 
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