Some questions about my water values

[KevinB]

Hey everyone,


I have the RSM 250 up and running for 3 months now. Added a Zebrasoma FL. on 02/11 and an Orange spotted diamond Goby on 27/11.
Now over the past 2 weeks, my Alk has been dropping and keeps dropping still, while my Mg and Ca are at a rather high level. I use Salifert test for all my tests and am 100% sure that I am using them correctly.
Values over the past weeks.

Date: 21/11

Alk: 8.9 dKH
Ca: 500
Mg: 1500
pH: 8.0


Date: 25/11

Alk: 8.0 dKH
Ca: 480
Mg: 1500
pH: 8.2


Date: 27/11

Alk: 7.3 dKH
Ca: 480
Mg: 1480
pH: 8.1


Date: 02/12

Alk: 6.8
Ca: 480
Mg: 1440
pH: 8.1




I do not dose anything to the system, except a 1 time solution against Red Cyano solutions, but that was after the drop already started.
I've been reading a lot about the water chemistry and although I have a brought knowledge about chem, I still am doubting if I should start dosing Alk alone or not?
Also doesn't normally Ca and Mg get consumed faster by coralline algae?

Any advise would be more than appreciated!


Cheers

Kevin

 

[reefer gladness]

My understanding was that large amounts of coralline increase the uptake of buffer (decreasing alkalinity) more than calcium and magnesium.

Regardless you want to keep alkalinity stable and in the 8-11dKH range. Generally when you have high levels of calcium as you do, lower levels of alkalinity are to be expected (and vice versa) but you still don't want alk below 8.0 in a reef tank. If regular waterchanges aren't keeping the chemistry stable then I would start dosing buffer to raise alk but do it gradually. Sudden increases (more than 1dKH over 24 hours) of alkalinity can bleach some corals.

 

[KevinB]

I still have Coral Buff from Red Sea that I did come with the RSM 250. Shall I try adding that ? (too bad the calculator tool doesn't list that product though)

 

[reefer gladness]

Sure it's okay, I used up the free stuff that came with my RSM tank too. Here's a link to the product page http://www.redseamax.com/languages%5C95%5Cpdf%5C155.pdf. I would start with about 20ml per day and test daily at first to see how much it's increasing the levels in your tank. When you reach you're target go back to testing every couple days until you get an idea of the uptake in your system. It's a young tank and the uptake of calc, alk and mag will fluctuate for awhile. I prefer to dose buffer in the morning before the lights come on when the pH is naturally at it's lowest point.

Everyone has their favorite brands, I switched over to Kent when the RS products ran out and they work pretty good for me. I have a pretty high uptake in my system and it's definitely cheaper for me to mix a measured amount of powdered Kent Superbuffer in RO/DI water daily than it would be to use a liquid solution.

 

[KevinB]

I'll keep that product in mind for when my RS stuff is used up, thanks!
I'll add 20ml each day then till I reach the target dkh and see in a week from now how it turns out with daily testing.

Thanks again.