Should I dose my water change water to get close to my tanks alk?

zafink

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So, I'm using tropic Marin pro reef, but the alkalinity is starts off at 7dkh, whereas I keep my tank at 10.5dkh. With my weekly 10% wc, it tends to lower my alkalinity by .7dkh. I am auto dosing my tank to maintain 10.5 dkh, and would prefer it not to drop whenever I do a water change for stability. (everything else from tropic Marin matches what I like to run)

So, am I worrying too much, or Does anyone else dose pre-water change? Or is there any significant reason to not to dose pre water change? haha

Input appreciated!
 

ReefRondo

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I’ve often wondered this but I assumed there would be higher chance of precipitation in my salt water storage tank and on heater etc.
 

Klyle

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Use soda ash to raise the alk of your wc water before you do a wc. Then again, .7 dkh drop shouldn't be too much of a concern.
 

Randy Holmes-Farley

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I recommend against soda ash.

Raw salt water is especially prone to precipitation of calcium carbonate (note the issues with the high alk mixes such as Red Sea Coral Pro or Instant Ocean). The reason is that it lacks organics and bacteria and phosphate that quickly coat seed crystals of calcium carbonate that form in a reef, preventing additional precipitation.

A better choice would be baking soda. You can boost alk as much as you want without getting the pH boost that accompanies washing soda. A 0.3 pH unit rise is equivalent to a doubling of alkalinity in terms of likelihood of precipitation, so keep pH low in high alk mixes. Add it after you have done most of your mixing and aeration to keep pH low and reduce precipitation.
 

Klyle

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I recommend against soda ash.

Raw salt water is especially prone to precipitation of calcium carbonate (note the issues with the high alk mixes such as Red Sea Coral Pro or Instant Ocean). The reason is that it lacks organics and bacteria and phosphate that quickly coat seed crystals of calcium carbonate that form in a reef, preventing additional precipitation.

A better choice would be baking soda. You can boost alk as much as you want without getting the pH boost that accompanies washing soda. A 0.3 pH unit rise is equivalent to a doubling of alkalinity in terms of likelihood of precipitation, so keep pH low in high alk mixes. Add it after you have done most of your mixing and aeration to keep pH low and reduce precipitation.
I stand corrected. Thanks for sharing this! I've been using soda ash and wondering why I get precip even with TM salts.
 

Harold999

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Yes, but I would argue to switch to a salt closer to your tanks DKH.

KH varies even from batch to batch of many brands, and certainly don't believe what they write on the bag or on their website. I always measure KH when opening a new bag and calculate how many baking soda i need to add to match the tankwater.
Happy corals.
 

Hydrored

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KH varies even from batch to batch of many brands. I always measure KH when opening a new bag and calculate how many baking soda i need to add to match the tankwater.
Happy corals.

I match it as well, going from 7 to 10.5 DKH was more my point, but to each is there own.
 

Harold999

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I match it as well, going from 7 to 10.5 DKH was more my point, but to each is there own.
I once bought a brand which claimed KH 9 on the bag, and i thought oh nice that's what my tank is. No more baking soda needed.
I tested it and it was 11.7 :(
 
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zafink

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Thanks for the advice Randy, and everyone else! Will be using baking soda to dose my wc water from now on
 

homer1475

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You can also lower alkalinity with muriatic acid, if you find your mix is too high.

I always doctor my mix to match my tank. Makes dosing easier when you do regular water changes.
 

GARRIGA

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Makes sense to prep replacement water to DT parameters plus what increase might be desired without causing shock to the inhabitants. One of the concerns I've always had with large water changes is the sudden shift in parameters. For small water changes such as 10%, I don't worry.
 

gbroadbridge

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So, I'm using tropic Marin pro reef, but the alkalinity is starts off at 7dkh, whereas I keep my tank at 10.5dkh. With my weekly 10% wc, it tends to lower my alkalinity by .7dkh. I am auto dosing my tank to maintain 10.5 dkh, and would prefer it not to drop whenever I do a water change for stability. (everything else from tropic Marin matches what I like to run)

So, am I worrying too much, or Does anyone else dose pre-water change? Or is there any significant reason to not to dose pre water change? haha

Input appreciated!
Match the Alk before doing the water change. Once you know the amount of Sodium Bicarbonate or Sodium Carbonate (Soda Ash) just add that amount with the salt to the mixing bucket every time.

I normally match Ca and Mg too as it's trivial to just add so many grams of each to the mix before doing the WC
 

sgrosenb

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I recommend against soda ash.

Raw salt water is especially prone to precipitation of calcium carbonate (note the issues with the high alk mixes such as Red Sea Coral Pro or Instant Ocean). The reason is that it lacks organics and bacteria and phosphate that quickly coat seed crystals of calcium carbonate that form in a reef, preventing additional precipitation.

A better choice would be baking soda. You can boost alk as much as you want without getting the pH boost that accompanies washing soda. A 0.3 pH unit rise is equivalent to a doubling of alkalinity in terms of likelihood of precipitation, so keep pH low in high alk mixes. Add it after you have done most of your mixing and aeration to keep pH low and reduce precipitation.
@Randy Holmes-Farley would you know if the Alkalinity component of ESV B-Ionic's 2-part would be an acceptable additive to use in order to raise dKH of Tropic Marin Pro-Reef replacement water-change water? I do weekly water changes and my tank water is at a dKH of 8.5 but TM Pro-Reef is closer to 7.0 dKH. If I add 20ml of ESV Alk component it rises the fresh TM Pro-Reef water-change water to 8.5 dKH, but I'm not sure if this is an appropriate route to take. Thank you for your help!

-Scott
 

Randy Holmes-Farley

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@Randy Holmes-Farley would you know if the Alkalinity component of ESV B-Ionic's 2-part would be an acceptable additive to use in order to raise dKH of Tropic Marin Pro-Reef replacement water-change water? I do weekly water changes and my tank water is at a dKH of 8.5 but TM Pro-Reef is closer to 7.0 dKH. If I add 20ml of ESV Alk component it rises the fresh TM Pro-Reef water-change water to 8.5 dKH, but I'm not sure if this is an appropriate route to take. Thank you for your help!

-Scott

If you do not see precipitation of calcium carbonate, it is fine. There will be some transient precipitation of magnesium hydroxide, but if that redissolves, you are good to go.

if you do see a permanent precipitate, baking soda is a better bet. :)
 

sgrosenb

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Thanks so much @Randy Holmes-Farley - a silly follow-up question - what would precipitation of calcium carbonate likely look like? Maybe a white-ish film in the water? Also - would there be an appropriate amount of time between when I add the ESV Alk and when I actually put the replacement water in my tank? Thanks again.
 

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