Kalk dosing causing PH to rise

[Wade]

I upped my kalk dosing slightly (4 heaping teaspoons for 7 gallons of top-off water). My alk and Ca have only very slightly increased (alk by maybe .2 - .5 dKh), but my PH has gone from 8.2 to 8.5. How high is too high for PH? I'd like to get my alk up to ~ 8 dKh. I've got 2 part, but I think I can get it there with the kalk. Should I use the 2-part to get it where I want it and then use the kalk to maintain? I know the 2-part will also cause the PH to rise which is why I ask how high is too high. I plan to do a water change tomorrow so maybe that will even it up a bit.

[Bogdan]

My tank pH fluctuates between 8.2 and 8.5. No reason to worry. I don't remember to cross any case of too high pH on a reef forum.

[Viet'spride70]

look like u r at a top of ph level...do u measure it at the end of photoperiod? if so, I say its a bit high but not in a danger zone.

this is just my opinion....

[subsea]

High pH, high calcium and high alkalinity are a disaster waiting to happen. If you have ever seen a snow storm in your reef tank, you will know what I am talking about.

Patrick

[ramsey]

Kalk will raise calcium and alkalinity levels in unison. It will also raise your ph (as you've noticed). 8.5 is fine but it's at the high end. I think the most important thing is not to swing your ph too much (and your alk!).

[subsea]

look like u r at a top of ph level...do u measure it at the end of photoperiod? if so, I say its a bit high but not in a danger zone.

this is just my opinion....

Actually, I saw it the other way. During the photoperiod, CO2 is consumed allowing the pH to rise naturally due to decrease in carbonic acid. If the pH were at 8.5 at the beginning of the photoperiod, it would rise during the photoperiod.

Wade,

Simply measuring one parameter like pH is incomplete to answer your general question. To be specific, alkalinity and calcium concentration are the two important parameters to know. While pH is simple to measure with a probe for continuous electronic monitoring, it is only a delayed indicator. Many hobiest, in an attempt to maximize coral production have seen the snow storm I alluded too. When calcium concentration and carbonate concentration, as measured by alkalinity, reaches the maximum of their solubility, then you will see the blizzard. Once it starts, it will run its course. A coating of calcium carbonate dust will cover every square inch of your reef tank.

Patrick

[Wade]

This reading was at the end of the photoperiod and fell steadily once the lights started to dim. Here's the Apex graph. The alk and Ca at that same time were measured to be 6.7 and 410. Would a high level of inorganic phosphates cause the PH to run high while doing kalk? I'm working on cleaning up my sb, but didn't want to be too aggressive with that and cause other problems. I plan to do about a 20% wc this evening or tomorrow morning and I'll do a good bit of stirring and vacuuming at that time. I've got some new SPS that have now been in my tank for 3 weeks and all are looking great so I want to make sure I make small adjustments. Will stirring up the sb cause any of my parameters to spike?

Apex.pdf

[ramsey]

Is that with the kalk dosing? Those numbers are a bit low but not bad IMO:

http://reefkeeping.com/issues/2004-05/rhf/index.php

I like keeping alk on the low side, around 7dkh. Also, those parameters will fluctuate if you're low on mag. You will want to check mag levels as well.

In regards to stirring the sand, I'm a big fan of stirring my sand bed and siphoning during a water change. There are varying opinions on this but it's what works best for me. However, I do this regularly (once every 1-2 weeks). If you don't stir it regularly, it could cause a spike in nitrate or even ammonia so be careful. A lot of detritus will build up in the sand if it's not stirred or if you don't have detrivores constantly cleaning it. I get a decent amount of detritus out of mine in just a weeks time and that's with ceriths, dwarf ceriths and nassarius snails, along with various worms, digging around in it.

[subsea]

This reading was at the end of the photoperiod and fell steadily once the lights started to dim. Here's the Apex graph. The alk and Ca at that same time were measured to be 6.7 and 410. Would a high level of inorganic phosphates cause the PH to run high while doing kalk? I'm working on cleaning up my sb, but didn't want to be too aggressive with that and cause other problems. I plan to do about a 20% wc this evening or tomorrow morning and I'll do a good bit of stirring and vacuuming at that time. I've got some new SPS that have now been in my tank for 3 weeks and all are looking great so I want to make sure I make small adjustments. Will stirring up the sb cause any of my parameters to spike?

Inorganic phosphate does not cause pH to rise during kalk dosing. Consider the pH and constituents in lime water, calcium hydroxide is very caustic. On its own merit, the pH will rise. In fact, this is the biggest contributor of calcium phosphate precipitation in substrate and on rocks. If your inorganic phosphate is elevated in the tank water, in the immediate area of kalk addition, the elevated pH can and will precipitate out calcium phosphate. This is a well documented and acceptable reef husbandry practice for removing inorganic phosphate from the water. I do not like it and I do not dose kalk. If you follow the chemistry, when elevated phosphate combines with calcium the cumulative effect is for alkalinity to decrease and for pH to follow.

Wade,

In answer to your question about pH and inorganic phosphate, it is the exact opposite. The chemistry pushes pH to drop.

Patrick

[Wade]

I guess this is a good sign that what I've been doing to clean the substrate is indeed lowering my inorganic phosphate. At this moment, my PH is 8.4. I received my new test kits in the mail this weekend. Alkalinity tested with the Hanna is 9 dKH ans the Ca tested with Salifert at 450. I would like to bring the alkalinity down to the 7 - 8 range, but not exactly sure how to do that slowly. My salinity also tested low and I'm not sure how that happens. Was 1.025 two weeks ago and today it's 1,0225 - 1.023. My ATO keeps the water level pretty stable. Weird.

[subsea]

It is normal for alkalinity to drop if the inhabitants are using calcium to grow. That is why you dose kalk. In my case, I use aroggonite substrate with a DSB. Consider that salinity is composed of dissolved minerals in the water. If those minerals are being deposited out to grow your SPS, the salinity will decrease unless you are adding minerals from another source.

In my outside growout systems, I use evaporative cooling which should have a tendency to increase salinity. My makeup water from the Middle Trinity is high in calcium, magnesium and sulphur another reason salinity should increase, yet it keeps coming down. Both corals and macro are composed of calcium, magnesium, sulphur, iron and many other trace minerals. The salinity is going into coral and macro biomass.

Now you know the rest of the story.

[Wade]

As always, you are a wealth of information. Thanks Patrick! Now to get ready for Game of Thrones!