Alkalinity iin my tank

Why? Any reason for this?

 

No particular reason outside of the recommendations of hobbyists. Natural sea water sits at about 7, so it certainly won't hurt anything to stay where he's at. Randy Holmes-Farley recommends anywhere between 7-11, so I shoot for the middle (9) rather than the upper or lower range.

 

According to Randy Holmes, to keep your water balanced, at a calcium level of 450, you should be around 4.5 meq/L or 12.6 dKh. I think Reef Crystals has an alk around 12 dKh at 35ppt IIRC, so something is still off I think as to why it is so low compared to calcium. Since you did not post it, what is your tank temp & pH at?

 

I had an issue with Sailfert and Red Sea alk test. What I would do is next time you mix your saltwater, check the brand's constants for alk such as @1.024 7 dkh @1.025 8 dkh or whatever it is and then perform both test kits to see which is closest. Now you batch might be a bit off, but this is the closest to a standard I think you will find.

I dont know why i didnt do this lol.

 

Oh, I forgot to ask, do you dose anything for calcium and/or alk right now? Or just water changes?

 

I do add a teaspoon of buffer to my top off which keeps my ph very steady.

My temp is at a constant 79 degrees and i have not checked ph lately but it usually is around 8.0 - 8.2 "I THINK". Ill have to check when i get home tonight.

I do does Bi Ionic 2 part when needed. Everything stays pretty consistent with little dosing.

 

I'm not sure exactly what Randy said or why, without a reference. However, the relationship between ca and alk, is not really important, as long as you have sufficient ca and alk and mg to maintain them in solution. So, having 450 and 12.6 dKh is not important at all, as long as you have over roughly 7dkh and over about 380 ca, and sufficient magnesium to maintain these levels in solution, then this is perfectly reasonable.

As to RC, at 1.0264 (35ppt) it should mix to about 490ppm ca, and 13dkH and 1440ppm mg.

However, corals will use 2.8dkh of alk for every 20dkh. So, from the numbers in post #8, if your ca is 450, from 490, then you'd expect your alk to be at 7.4. Test kits aren't perfect, so, 7.8 certainly seems about right to me, without dosing (I'm not sure how much you dose etc... so may be right with dosing depending on the numbers) Mg, seems a bit high, but really isn't used fast and mg test kits aren't necessarily that accurate either, and tend to be difficult to use.

 

Sorry, I included it in a Hyperlink:

Excellent point, I had not thought of that.