Reef Central Online Community

Go Back   Reef Central Online Community > General Interest Forums > The Reef Chemistry Forum
Blogs FAQ Calendar Mark Forums Read

Notices

User Tag List

Reply
Thread Tools
Unread 04/26/2020, 10:03 AM   #1
big_ben102000
Registered Member
 
Join Date: Oct 2006
Posts: 6
Chemistry calculations

hi all,

I recently started dosing sodium bicarb, CaCl2, MgCl2 and Na(NO3).4H2O. I am trying to dial in the dosing calculation.

1g of solute in 1000L of water should give 1ppm/L. but does the molecular weight of the molecule has an effect on the overall ppm/L

thanks !


big_ben102000 is offline   Reply With Quote
Unread 04/26/2020, 12:42 PM   #2
bertoni
RC Mod
 
Join Date: Mar 2002
Location: Mountain View, CA, USA
Posts: 88,616
1g per 1000L is 1 ppm, always, but if you want 1 ppm of calcium and are using calcium chloride, you need to remember that calcium chloride (anhydrous) is only 36% calcium by weight. So it'd be 2.8 mg/L to get 1 ppm calcium. Does that answer your question?


__________________
Jonathan Bertoni
bertoni is offline   Reply With Quote
Unread 04/26/2020, 08:59 PM   #3
big_ben102000
Registered Member
 
Join Date: Oct 2006
Posts: 6
hi Jonathan,

yes, but do we need need to consider the Ca reacting with other components in the reef tank that might reduce or increase the variable Ca ?

my readings of Mg is a little off after dosing


big_ben102000 is offline   Reply With Quote
Unread 04/27/2020, 11:20 AM   #4
bertoni
RC Mod
 
Join Date: Mar 2002
Location: Mountain View, CA, USA
Posts: 88,616
I am not sure what you mean. The calcium (or magnesium) will be consumed at some rate by the tank, so measuring fairly shortly after dosing is a good idea. It only took 10 seconds or so for the calcium supplement to mix into my 29g tanks, so I measured very soon after dosing. A larger tank with a large sump might require a bit more time.


__________________
Jonathan Bertoni
bertoni is offline   Reply With Quote
Unread 05/25/2020, 08:32 PM   #5
big_ben102000
Registered Member
 
Join Date: Oct 2006
Posts: 6
I am dosing CaCl2, MgCl2 and Na(NO3).4H2O at the moment.
for CaCl2 anad Na(NO3).4H2) the theoretical calculation in ppm increase pretty much matches the actual water testing before and after adding (give or take some ppm.. since hobbyist kits aren't the most accurate) but the MgCl2 the measurements seem to be way off from theoretical calculations.

any opinions ?


big_ben102000 is offline   Reply With Quote
Unread 05/26/2020, 01:50 PM   #6
bertoni
RC Mod
 
Join Date: Mar 2002
Location: Mountain View, CA, USA
Posts: 88,616
How far off are the test results? You might have a bad test kit.


__________________
Jonathan Bertoni
bertoni is offline   Reply With Quote
Unread 05/30/2020, 07:33 AM   #7
big_ben102000
Registered Member
 
Join Date: Oct 2006
Posts: 6
hi Jonathan, the readings were over by about 3 folds.
in the last couple of days. I was able to get the my calculation reading to match the test kit reading. i am using salifert btw. I waited 2 hrs before taking a reading again. previously was 10-15 mins.

thank you for the inputs


big_ben102000 is offline   Reply With Quote
Unread 05/30/2020, 04:35 PM   #8
bertoni
RC Mod
 
Join Date: Mar 2002
Location: Mountain View, CA, USA
Posts: 88,616
Okay, if you are getting matches now, I guess I wouldn't worry. The Salifert kit should be good to within 15 ppm or so if it's used carefully.


__________________
Jonathan Bertoni
bertoni is offline   Reply With Quote
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



All times are GMT -6. The time now is 10:02 AM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2024 Axivo Inc.
Use of this web site is subject to the terms and conditions described in the user agreement.
Reef CentralTM Reef Central, LLC. Copyright ©1999-2022
User Alert System provided by Advanced User Tagging v3.3.0 (Pro) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.