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2639
08-20-2005, 12:04 PM
I just took some readings:
Alk = 4.11 meq/L
DKh = 11.5
Calcium = 410 ppm
PH = 8.2

Is the Alk high? I've NSW has 2.9 for alk
If so, how do I lower it but keep the other parms the same?
Doctor_Reef
08-20-2005, 12:22 PM
Yep....Looks fine....I like to keep my Calcium up just a tad higher...but you are ok....Mine is always about 430 or so.....
2639
08-20-2005, 01:11 PM
so there is no harm in the alk being so high?
Doctor_Reef
08-20-2005, 02:42 PM
No...not at all you can keep alk between 3.3 and 5.0 and you are usually fine...DKH under 12 you are good....
MikeS
08-20-2005, 11:21 PM
2639...what is your gravity at? You want to base your Ca and Alk on these as well....

MikeS
2639
08-20-2005, 11:23 PM
I try to maintain an SG of 1.023 I chose that because it's in the middle of the recommended values.
MikeS
08-21-2005, 12:14 AM
Ok...1.023 SG is around 31 ppt salinity. At 31 ppt salinity, an equivilent Ca/alk level would be 370/2.0 dKH. Obviously not the recommended leves you are used to seeing, but nonetheless in proportion for your particular salinity. You have 410ppm Ca, 11.5 dKH (4.1 meq/L) @ 1.023. You have an imbalance, at 410 Ca your alk is too high, it needs to be around 7 dKH.

Also, if you want to run a Ca of 410ppm, your SG needs to be around 1.025. Don't be afraid of this level, NSW is 1.026....

Mike
JmusicB
08-21-2005, 12:23 AM
Mike S,.....do you have an article reference for the relationship between SG an CA/ALK? I have never heard that before and would like to read up on it.

Thanks
2639
08-21-2005, 12:45 AM
As I...Also, how do you manipulate one parameter but leave the others alone ie. lower alk but leave ph alone?
MikeS
08-21-2005, 01:18 AM
Mike S,.....do you have an article reference for the relationship between SG an CA/ALK? I have never heard that before and would like to read up on it.

Thanks

No...I don't have an article to reference on that, but it is just a simple ratio thing I happen to be a very firm beleiver in...ie the precentage of Ca in a 35ppt solution vs a 31 ppt salinity solution...I think we really need to shoot for NSW values, or equivilent ratios of NSW values based on salinity....I think these values need to be maintained in a proportionate ratio to NSW....there are many out there who agree with this principle...

Also, how do you manipulate one parameter but leave the others alone ie. lower alk but leave ph alone

Well, that is difficult considering they are all related...there are many factors that play into it. If your pH is in a good range (8.1-8.4) and properly buffered, you have nothing to worry about.

MikeS
2639
08-21-2005, 01:30 AM
So even though there is an imbalance, there really isn't a whole lot that can be done right? I'd like to achieve the values of nsw too. I feel more comfortable shooting for something that has worked for eons ;)
Doctor_Reef
08-21-2005, 11:01 AM
I would agree with Mike on the alk at your SG....and his recomendation should be your goal here...but a dKH between 8-12 will certainly not hurt anything even at your present SG so don't panic about it...As your tank settles in it will come down to the right level....

In Eric Borneman’s...book Aquarium Corals...He says the alkalinity of natural seawater is about 2.5 meq/L, although the comparative high bioload of aquariums makes a slightly higher level of 3.2-4.5 meq/L beneficial to the system as a whole...

Carbonate hardness on the reef typically measures 7-8 dKH, with a range of 7-12 dKH generally recommended for aquarists...

If your tank has a low bio-load it is easier to keep it close to nsw...but if you are like 90% of reef keepers today....well!!! ;)