alkalinty and ph levels

[mattseattle]

ok newbie question:

what are the recommended levels for ph and alkalinity.

i've read 2.3 up to 3.3 for alkalinity and ph from 8.0 - 8.4. the label on the kent superbuffer says the recommended #'s are ph 8.0 - 8.3 and alk for reef tanks should be 2.9 - 4.0 meq/l or 8 - 11 dKH

my ph is running about 8.2 - 8.3 and my alkalinity looks like about 3.2 or a tad less. i've been using the kent ph/alk buffer on a weekly basis.

thanks!

 

[steve-s]

The alk and ph are fine but it really depends on what the calcium is to determine if it's properly balanced against the alk. Personaly I keep my alk about 11 DKH (3.93 mEq/l) and my Ca between 425-440ppm.

If your alk is 3.2 meq/l, then a balanced Ca would be between 420-430ppm. Make sure your magnesium is also up to par (1300-1500ppm) or you will end up with constant chem problems.

>>Here<< is a great learning article that should help you. There are many contraditions as far as chem levels are concerned and how you administer them. It's just a matter of finding something that suits yours and the tanks needs.

Cheers
Steve

 

[mattseattle]

my calcium is right around 400. i don't have a test kit for magnesium...guess that is my next purchase then!

 

[mojoreef]

Steve gave you some great info Matt. if you are a regular water changer you mag level should be fine. But it does play a large role in your water chemistry as Steve said. Everything will eventually depend on your bioload and what demands it puts on your water. So for now you are pretty darn close.
As an example of differing tanks and what we run them at. I run my dkh at 13 and up and try to keep my cal always over 460. But that is done that way because of the bioload and typing of corals I keep.


mike

 

[steve-s]

if you are a regular water changer you mag level should be fine.

I would actually suggest confirming that depending on the salt you use as many are deficient in mag. Kent and IO from my experience are fine but I am unsure of others.

Cheers
Steve

 

[kevinpo]

Just as a reference NSW (Natural Sea Water) runs about 400 ppm calcium and 2.8 meq/L alkalinity. The more you deviate from these values the more unstable your chemistry becomes which means you have to test and/or dose regularly in balanced amounts. It does little good to have one high and the other low.

Regards,
Kevin

 

[mattseattle]

right now i'm buying my water from the seattle aquarium. and you are right it's been testing at around 400 or so.

 

[tdwyatt]

Just as a reference NSW (Natural Sea Water) runs about 400 ppm calcium and 2.8 meq/L alkalinity...

It will not really matter to the stability of your calcium nor alkalinity levels if they are allowed to drop to the 350 PPM Ca/ 2.5 mEq alk range in and of itself, although it may make it difficult for the levels to go back up to where we want them. In FO systems this will not really have much impact on the coralline nor to snails, etc. so long as the Ca does not drop below the 350 or so level. It IS tough on any hermatypic corals, clams, and any octocorals that use the Ca and alk to make spicules in their coenenchyme (mesoglea). For those organisms that use large amounts of these substances to make either shells, tests, spicules or CaCO3 skeletons, higher Calcium in the 400 PPM+ range and matching Alkalinity in the 12+ dKh range will promote faster growth and help assure that our specimens thrive. Supplementations that are not balanced or involve additions to systems that are either too much Calcium and/or too much alkalinity (usually bicarb or sodium carbonate) may result in water column imbalances and inability to attain the higher levels desired for hermatypic organisms. In FO systems, the 350PPM levels are more than adequate, and will suffice for those systems.

Magnesium is required to "poison" the development of crystals of Calcium Carbonate, providing for the means of supersaturating the water column in respect to Calcium in association with bicarbonate/carbonate (the most reactive spp after phosphate as determed by pKa of these substances in seawater). Allowing the Mg level to drop below 1300 (watch sulfate as well, but that is another story) will reduce your overall ability to attain Ca levels (400PPM+) and alk levels(in excess of 12 dKh) we desire. This often occurs when using 2 part additives in systems without regular water changes. By the same token, allowing salinity to creep downward will reduce the concentration of those substances which facilitate supersaturation of the water column by Calcium (do the math, drop your salinity by 10% = Mg going from 1300 to 1170) Just correcting a SG problem will often correct problems attaining supersaturatioin of the water column by Ca and carbonate/bicarbonate.

HTH

 

[mojoreef]

Great reply Tommy

MIke