Did a water change, checked Alk, added Kent buffer, and now alk is even lower

[gsxrguru2]

So this being a very new system, I am not sure if maybe I went wrong somewhere. I did a 30g water change and checked the alkalinity afterwards. It measured at 6.9 I added 6 capfulls of kent Pro-buffer dKH and checked it about 10 min later with the salifert KH testkit. It measured 5.8 this time around. I was using Kent seasalt, I have a 125g tank with only LR so far, the only habitants are hitchikers. Any ideas why this happened and what I should do? Thanks!

 

[reefshadow]

Could be a test error.

If you are currently cycling the live rock in the display, it would be expected to see a rather sharper decline in alkalinity and ph over time than in a mature tank.

Fwiw, I think commercial preperations are next to useless for the money you spend on them. You can make your own nearly identical preperation using arm and hammer pure baking soda or baking and washing soda in a 5:1 ratio (better for boosting a lower ph). In some cases a home brew is safer, as some retail mixes use borates, and the arm and hammer is food grade, versus an unknown grade in the commercial preps.

Not sure of the strength, 6 capfuls doesn't seem like much in what is essentially a 165 gallon system.

 

[gsxrguru2]

Each capful is good for 20gal so I figured I'd start on the low end and see what happened. My protein skimmer is certainly going crazy right now though... Using baking soda in the 5:1 ratio you're talking about, will that do much to the pH if it is already at 8.2? I'm just trying to raise the alkalinity. I think I'll wait a bit and try testing again also, it just seems so weird that it would drop the alk when it is supposed to raise it. oh well, we'll see what happens here...

 

[reefshadow]

Just using pure baking soda will not raise the ph. Adding the washing is good for boosting it as well as the alk though, if needed.

I wonder if the results on your initial test were skewed for whatever reason. There can be alot of variables from test to test, though salifert makes good tests (acids added from your hands, residue in the vial or cup, erronious calculation, ect..). I really doubt if your supplement actually lowered the alk. Probably something else going on here...

 

[3D-Reef]

Have you checked your magnesium level?
If mag is too low the carbonates have a hard time staying in the water column.

 

[gsxrguru2]

Don't have a mag test kit, but I just ordered one though. Do you guys have any links to either threads or sites that explain how all the water chemistry stuff works? I'm trying to figure out how all this stuff works and correlates with each other (like magnesium- how does that work with calcium and whatever else?) Thanks for all the help!

 

[reefshadow]

Randy Holmes has done alot of great articles for reefkeeping magazine on chemistry. If you do a search using his name you should get lots of links to them. Sorry, I don't have time right now to hunt them down and link them for you but a search on Yahoo or similar should be easy.

 

[man1410]

Ask Randy Holmes in the chemistry forum!

 

[gsxrguru2]

I will do that! Thanks for helping me out on this one

 

[gsxrguru2]

Found exactly what I was looking for in the chemistry forum. Thanks!