Alkalinity won't go down

[gaby_scan]

Hello all, i've been struggling with my alkalinity for a while now, the lowest it has been is 11 and it is constantly 12...is there any way i can lower my alkalinity to single digits? I don't think my lps corals like it, my xenias and softies don't seem to care much about it but my hammer and torch just won't open. I have been strictly doing my water changes weekly and the salt i use is red sea, before i used instant ocean but i change it to see if that was my reason of my high alk. Tank is been running for 7 months.

Parameters:

1.026 salinity
500 calcium
8.0 ph
12 alk
0.03 phosphate
5ppm nitrate

 

[Uncle99]

Red Sea Black results in 11.5 Alk
Try Red Sea Blue, if ya like Red Sea.
IO and RC both have lower Alk

 

[gaby_scan]

Red Sea Black results in 11.5 Alk
Try Red Sea Blue, if ya like Red Sea.
IO and RC both have lower Alk

Yes i have the red sea blue, still my alk keeps steady at 12 :headwally:

 

[wrott]

You could dose vinegar until alk starts to drop, then stop at 9-10 dKH.
You may see cloudy bacterial bloom, use airstone if fish get distressed.

 

[gaby_scan]

You could dose vinegar until alk starts to drop, then stop at 9-10 dKH.
You may see cloudy bacterial bloom, use airstone if fish get distressed.

Hmmm sounds promising...i was filling my rodi bucket and i decided to test the water of my reservoir. It says that my rodi water has 5dkh. I'm using red sea tests, is that ok or my rodi system is supposed to get me 0dkh? Please advice thank you

 

[otimer]

Theoretically dt alkalinity drops as per the equation ;
alk2(dt)=alk1(dt)-(alk1(dt)-alk(sw))*%(wc)/100
Where,
alk1(dt) : dt alkalinity before water change
alk2(dt) : dt alkalinity after water change
alk(sw) : new salt water alkalinity
%wc : water change percentage

It means for example, your tank alk is 12, new saltwater alk is 8, than the difference is 4dkh.
If you perform 10% water change, tank alk after wc must be 11.6dkh.
Also tank live stock consume alk till next water change.
You'd rather check the test instrument/kit of salinity, alkalinity and/or what you are dosing.

 

[droog]

Test the make up water. Red sea salt blue bucket mixes to a dKH of 8.1 pretty consistently for me. (Red Sea Coral pro is much higher)

Maybe your test kit went bad, it does happen, either the alk test or the salinity test method. Hanna checker I think is the best for Alk and the digital refractometer for salinity.

In terms of what to do - dong nothing is probably best. Only thing worse than high alk is a rapidly changing alk. Worst case do less frequent and/or smaller water changes.

-droog

 

[gaby_scan]

Theoretically dt alkalinity drops as per the equation ;
alk2(dt)=alk1(dt)-(alk1(dt)-alk(sw))*%(wc)/100
Where,
alk1(dt) : dt alkalinity before water change
alk2(dt) : dt alkalinity after water change
alk(sw) : new salt water alkalinity
%wc : water change percentage

It means for example, your tank alk is 12, new saltwater alk is 8, than the difference is 4dkh.
If you perform 10% water change, tank alk after wc must be 11.6dkh.
Also tank live stock consume alk till next water change.
You'd rather check the test instrument/kit of salinity, alkalinity and/or what you are dosing.

I've already check with more than 1 test kit with the same results. Not dosing anything on the tank, but if my red sea salt says alkalinity is 8 and the water i'm getting from my rodi is 5, doesn't that mean that there is something wrong with my rodi unit? Shouldn't it be lower?

 

[gaby_scan]

Test the make up water. Red sea salt blue bucket mixes to a dKH of 8.1 pretty consistently for me. (Red Sea Coral pro is much higher)

Maybe your test kit went bad, it does happen, either the alk test or the salinity test method. Hanna checker I think is the best for Alk and the digital refractometer for salinity.

In terms of what to do - dong nothing is probably best. Only thing worse than high alk is a rapidly changing alk. Worst case do less frequent and/or smaller water changes.

-droog

Yes i have never tested the make up water for alk, gotta do it next time i do a wc.

 

[otimer]

I've already check with more than 1 test kit with the same results. Not dosing anything on the tank, but if my red sea salt says alkalinity is 8 and the water i'm getting from my rodi is 5, doesn't that mean that there is something wrong with my rodi unit? Shouldn't it be lower?

The alkalinity of your red sea salt would be about 8.0 dkh. Even if the rodi reading is 5, it is not alkalinity, but it's Total Desolved Solid in ppm. You may consider 0 alkalinity of your rodi.
Double heck your salinity as well.
Also measure alkalinity of both your system water and new makeup water.

 

[wrott]

Did you measure TDS and dKH of your ro/di water?
If dKH is not 0, then yes there's a problem.

 

[gaby_scan]

The alkalinity of your red sea salt would be about 8.0 dkh. Even if the rodi reading is 5, it is not alkalinity, but it's Total Desolved Solid in ppm. You may consider 0 alkalinity of your rodi.
Double heck your salinity as well.
Also measure alkalinity of both your system water and new makeup water.

Will do thank you

 

[gaby_scan]

Did you measure TDS and dKH of your ro/di water?
If dKH is not 0, then yes there's a problem.

Yes rodi water reads 5dkh

 

[wrott]

Then your TDS should be >100ppm.
When did you change filters last and do you have a TDS meter?

 

[gaby_scan]

Then your TDS should be >100ppm.
When did you change filters last and do you have a TDS meter?

It's been a while, maybe that can be the problem, possibly that is the problem. No tds

 

[gaby_scan]

I just did new water at 1.026 salinity and red sea says it should give me 8dkh. Well my dkh test came at 11 so that is why my alk is steady in the 11-12 range...the only think i can think of is my filters in my rodi unit are bad and need to be changed, please advice. Thank you

 

[wrott]

Yes, try to get a TDS meter or borrow one from LFS to confirm before and after changing filters.
You'll figure it out, good luck!

 

[gaby_scan]

Yes, try to get a TDS meter or borrow one from LFS to confirm before and after changing filters.
You'll figure it out, good luck!

I will, thanks a lot wrott hope this fix my problem with my dkh.

 

[wrott]

Happy reefing!
This is what i use:
https://premiumaquatics.com/products/hm-digital-dm1-inline-dual-tds-monitor.html
Change battery every few years.

 

[droog]

The inline meter is good - the cheap and cheerful way is a simple "pen" type device, like this one for $7 and simply test the water coming out of your RODI unit. Test your tap water too!

Maybe your RODI unit needs replacement, some of them ship with built in TDS meter(s)

-droog