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Unread 05/18/2019, 03:13 PM   #1
gaby_scan
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Alkalinity won't go down

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


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Unread 05/18/2019, 04:59 PM   #2
Uncle99
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Red Sea Black results in 11.5 Alk
Try Red Sea Blue, if ya like Red Sea.
IO and RC both have lower Alk


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Unread 05/18/2019, 07:09 PM   #3
gaby_scan
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Quote:
Originally Posted by Uncle99 View Post
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


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Unread 05/18/2019, 10:49 PM   #4
wrott
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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.


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Unread 05/19/2019, 05:14 AM   #5
gaby_scan
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Quote:
Originally Posted by wrott View Post
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


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Unread 05/19/2019, 05:30 AM   #6
otimer
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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.


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Unread 05/19/2019, 05:36 AM   #7
droog
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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


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Unread 05/19/2019, 05:38 AM   #8
gaby_scan
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Quote:
Originally Posted by otimer View Post
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?


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Unread 05/19/2019, 05:41 AM   #9
gaby_scan
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Quote:
Originally Posted by droog View Post
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.


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Unread 05/19/2019, 06:53 AM   #10
otimer
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Quote:
Originally Posted by gaby_scan View Post
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.


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Unread 05/19/2019, 07:51 AM   #11
wrott
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Did you measure TDS and dKH of your ro/di water?
If dKH is not 0, then yes there's a problem.


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Unread 05/19/2019, 08:29 AM   #12
gaby_scan
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Quote:
Originally Posted by otimer View Post
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


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Unread 05/19/2019, 08:30 AM   #13
gaby_scan
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Quote:
Originally Posted by wrott View Post
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


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Unread 05/19/2019, 09:16 AM   #14
wrott
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Then your TDS should be >100ppm.
When did you change filters last and do you have a TDS meter?


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Unread 05/19/2019, 11:39 AM   #15
gaby_scan
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Quote:
Originally Posted by wrott View Post
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


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Unread 05/19/2019, 11:42 AM   #16
gaby_scan
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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


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Unread 05/19/2019, 12:00 PM   #17
wrott
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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!


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Unread 05/19/2019, 12:08 PM   #18
gaby_scan
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Quote:
Originally Posted by wrott View Post
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.


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Unread 05/19/2019, 01:27 PM   #19
wrott
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Happy reefing!
This is what i use:
https://premiumaquatics.com/products...s-monitor.html
Change battery every few years.


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Unread 05/19/2019, 06:58 PM   #20
droog
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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


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Unread 05/19/2019, 10:27 PM   #21
laverda
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Something is definatly wrong with you RO/DI system. The DKH coming out of it should be zero. That is high enough I wonder if your output and waste lines are mixed up coming out of you RO membrane. What is the DKH of your tap water? My guess is 5 or a little lower.

You can use a few small amount of Muriatic acid to lower the DKH of your new salt water. There is a thread in the chemistry forum about how to reduce your ALK. Also lowering your salinity to 1.025 will help a little.


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Unread 05/20/2019, 12:09 AM   #22
droog
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Testing dKH of RODI water using a saltwater test kit might not give a "valid" result.

Testing TDS of your RODI is absolutely valid. TDS of water from your RODI water should be close to zero (or actually zero if you run a DI stage). If you never change the DI resin, I believe it can leak ions into the output water. Perhaps thats your problem.

-droog


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Unread 05/20/2019, 05:52 PM   #23
gaby_scan
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Quote:
Originally Posted by laverda View Post
Something is definatly wrong with you RO/DI system. The DKH coming out of it should be zero. That is high enough I wonder if your output and waste lines are mixed up coming out of you RO membrane. What is the DKH of your tap water? My guess is 5 or a little lower.

You can use a few small amount of Muriatic acid to lower the DKH of your new salt water. There is a thread in the chemistry forum about how to reduce your ALK. Also lowering your salinity to 1.025 will help a little.
Well i haven't check my dkh of my tap water and i don't wanna use my saltwater dkh test kit on that, not sure how accurate it is, outputs of the ro are good, that was the first thing i checked lol. Yes that is what i did i use muriatic acid in a 5 gallon water change, my dkh tested 11 and after 3.6mls of muriatic acid it went down to 8
...the ph drop a lot so i left it overnight with a powerhead to raise it ,today it was 7.8 which is pretty close to what my tank is, all in all it went well. Also i ordered a tds meter so i will check where my ro/di is sitting at, i'm pretty sure the filters are bad, haven't changed them in a while


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Unread 05/20/2019, 05:55 PM   #24
gaby_scan
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Quote:
Originally Posted by droog View Post
Testing dKH of RODI water using a saltwater test kit might not give a "valid" result.

Testing TDS of your RODI is absolutely valid. TDS of water from your RODI water should be close to zero (or actually zero if you run a DI stage). If you never change the DI resin, I believe it can leak ions into the output water. Perhaps thats your problem.

-droog
Tds on the way, yes haven't changed anything in a while. Pretty sure that is the culprit here.


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Unread 05/29/2019, 08:24 PM   #25
droog
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Just curious... what happened in the end?

-droog


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