Should I dose Alk?

[Fishbro]

Hey everyone so in my Biocube 32 I think it’s time to dose and I have BRS two part. I’m using reef crystals which I believe mixes to 12. I just tested today and my Alk is 9.3 and I did a water change two days ago. Should I dose start dosing Alk to bring it to 12? Sorry I’m just insanely confused. I tested every day for a week and my results were just confusing too. My Alk somehow went down then up even though I didn’t do a water change.

 

[Chefwheredyougo]

I suggest you test your fresh mixed SW, and your tank separately, then the tank afterwards. Then do so the next day at the same time.

 

[Randy Holmes-Farley]

Hey everyone so in my Biocube 32 I think it’s time to dose and I have BRS two part. I’m using reef crystals which I believe mixes to 12. I just tested today and my Alk is 9.3 and I did a water change two days ago. Should I dose start dosing Alk to bring it to 12? Sorry I’m just insanely confused. I tested every day for a week and my results were just confusing too. My Alk somehow went down then up even though I didn’t do a water change.

12 dKH seems high as the goal for a general reef tank.

The alk changes were most likely due to variability in the test, not in the actual alkalinity.

7-11 dKH is a fine range. letting it drop from where it is now is OK.

 

[Fishbro]

12 dKH seems high as the goal for a general reef tank.

The alk changes were most likely due to variability in the test, not in the actual alkalinity.

7-11 dKH is a fine range. letting it drop from where it is now is OK.

Ok so is there a certain target you recommend hitting for Alk? Is 10 ok?

 

[Randy Holmes-Farley]

Ok so is there a certain target you recommend hitting for Alk? Is 10 ok?

I'd suggest reading up on targets for calcium and alkaliniyy, and especially for alkalinity, why one might choose 7 dKH or 9 dKH or whatever, There are reasons for picking specific values, and they are not all equivalent.

This may be a good start on those ideas:

Optimal Parameters for a Coral Reef Aquarium: By Randy Holmes-Farley

[note: edited on 5/29/2022 to update the nitrate and phosphate sections with higher recommended levels.] One of the main roles of an aquarist with a coral reef aquarium is to ensure that the conditions are right for their tank inhabitants. There are many different attributes of the aquarium...

www.reef2reef.com

 

[Fishbro]

I'd suggest reading up on targets for calcium and alkaliniyy, and especially for alkalinity, why one might choose 7 dKH or 9 dKH or whatever, There are reasons for picking specific values, and they are not all equivalent.

This may be a good start on those ideas:

Optimal Parameters for a Coral Reef Aquarium: By Randy Holmes-Farley

[note: edited on 5/29/2022 to update the nitrate and phosphate sections with higher recommended levels.] One of the main roles of an aquarist with a coral reef aquarium is to ensure that the conditions are right for their tank inhabitants. There are many different attributes of the aquarium...

www.reef2reef.com

Ok thank you that explained it really nicely. So I’m just confused on another thing. I’m deciding whether I want my Alk to be 9 or 10 but I I’m thinking closer to ten since I’ll have mostly LPS in the future. I know Reef Crystals mixes to a really high Alk, will it matter if when I do a water change it’ll raise my Alk higher than 10? Or do I just need to test my fresh saltwater and see what it really mixes to?

 

[Chefwheredyougo]

Test your fresh saltwater. Depending on how what dKH and how big of a water change, you can figure out how much it will impact your tanks alkalinity.

 

[Randy Holmes-Farley]

Ok thank you that explained it really nicely. So I’m just confused on another thing. I’m deciding whether I want my Alk to be 9 or 10 but I I’m thinking closer to ten since I’ll have mostly LPS in the future. I know Reef Crystals mixes to a really high Alk, will it matter if when I do a water change it’ll raise my Alk higher than 10? Or do I just need to test my fresh saltwater and see what it really mixes to?

There is no evidence (IMO) that 7 or 9 or 11 dKH is "best" for LPS.

Just because RC mixes to a high alk does not mean the tank needs to be high. But if you keep the tank at 7 dKH, you wouldn't want to do very large water changes due to the sudden alk rise. If the tank is 7 dKH and the mix is 12 dKH, a 10% water change only boosts alk from 7.0 to 7.5 dKH, which is fine. At higher tank starting alk, the boost is even smaller.

 

[PatW]

There is no evidence (IMO) that 7 or 9 or 11 dKH is "best" for LPS.

Just because RC mixes to a high alk does not mean the tank needs to be high. But if you keep the tank at 7 dKH, you wouldn't want to do very large water changes due to the sudden alk rise. If the tank is 7 dKH and the mix is 12 dKH, a 10% water change only boosts alk from 7.0 to 7.5 dKH, which is fine. At higher tank starting alk, the boost is even smaller.

I use RC and on water changes, I just do it straight. The water change just works as a maintenance dose for that day.

 

[Randy Holmes-Farley]

I use RC and on water changes, I just do it straight.

I'm not sure what that means, but my point was just that you need not switch to a different mix to keep a lower alkalinity.

 

[Fishbro]

Ok so just so I’m clear. On Wednesday when I do my water change I test my fresh sw, tank before water change, then tank after water change? I just tested my Alk again and it was 8.5. I know I need to be dosing but shouldn’t how much be determined by what I want to keep my Alk at? So if I want my Alk to be at 10 shouldn’t I dose now to make it 10? Also, if I’m dosing everyday say 5ml (example not actual dose) on water change day my Alk gets boosted from dosing and the water change wouldn’t it be too high? Should I not dose on wc day?

 

[Randy Holmes-Farley]

Ok so just so I’m clear. On Wednesday when I do my water change I test my fresh sw, tank before water change, then tank after water change? I just tested my Alk again and it was 8.5. I know I need to be dosing but shouldn’t how much be determined by what I want to keep my Alk at? So if I want my Alk to be at 10 shouldn’t I dose now to make it 10? Also, if I’m dosing everyday say 5ml (example not actual dose) on water change day my Alk gets boosted from dosing and the water change wouldn’t it be too high? Should I not dose on wc day?

Certainly dosing is determined by what your target is. 10 dKH is a fairly high target and will take more dosing every day than maintaining 8 dKH, but yes, if that is your target, I'd be slowly raising the alk to get there and then keep it there.

 

[Fishbro]

Certainly dosing is determined by what your target is. 10 dKH is a fairly high target and will take more dosing every day than maintaining 8 dKH, but yes, if that is your target, I'd be slowly raising the alk to get there and then keep it there.

Ok great so if my reef crystals truly mixes to 12 wouldn’t it be better to have my Alk at 10 so water changes wouldn’t make a huge swing or if I’m only doing 15% water changes every week would it not make a difference if I chose say 9?

 

[Randy Holmes-Farley]

Ok great so if my reef crystals truly mixes to 12 wouldn’t it be better to have my Alk at 10 so water changes wouldn’t make a huge swing or if I’m only doing 15% water changes every week would it not make a difference if I chose say 9?

I would not set your alk target based on the salt mix. I'd either adjust the size of the water changes, or use a different mix. It is too important to let the salt manufacturer decide for you.