PH buffer and alk

[graffyn]

PH buffer and alk

I used a PH buffer to raise my PH, as well as using the 2-part B-ionic calcium buffer system. I then wound up with high alkalinity.

Since then, I have just used the calcium part of the B-Ionic, stopped using the alk part, and also stopped adding PH buffer.

My alk has dropped to nearly normal level (6 meg/l). Calc is pretty good (almost 400) and PH is a little low (maybe 7.8-7.9 morning and 7.9-8.0 evening).

Any ideas what I should be doing now?
And is there something other than PH buffer I should do to get the PH to rise....or is everything OK as is?

I have heard that I can use Kalk in all top-off water to raise the PH back up, will will this not also raise the Alk again?

Thanks, going crazy here

[m&m]

your p.h. and alk is low.try using kalk to replace evaporated water then retest to see were you are at.

[graffyn]

Actually natural seawater Alk is 2.5 to 3 meg/l and to the best of my understanding 4-6 is recommended in the Aquarium. I believe that 6 meg/l is about 14 dkh. which is still high.

[graffyn]

Ok OK, I am bowing down to the REEF GODS.............

How do you raise PH without raising Alk.

[105man]

I had the same problem, and never found an easy solution. All the advice was to do more water changes, for a while stop using the alk part of the B-Ionic (as you have), and stop using any of the PH buffers because they raise alk.

I guess the theory is that with more frequent water changes, the natural PH should be OK. Anyway, I think that modestly low PH that is relatively stable is better than dramatically varying the PH in an effort to get it to the supposedly best level.

[Geoff]

i have found toping off with Kalk is the only way to go. it replaces both Ca and alk in equal quantities, which is the way they are used up in the system.

you may need to do a water change to get things back to a base line.

i would just top off with kalk for a month and watch your levels. they should start leveling out to what you want. as my Ca munching critters get bigger i have to add a little Ca every now and then to get the Ca levels back up, but it is not by much. my alk has been staying fine.

do a search for kalk and Tom. hopefully you will find one of his many great posts on this problem.

G~

[tdwyatt]

Originally posted by graffyn
...How do you raise pH without raising Alk?

Keep in mind that pH Calcium, alkalinity, and the concentration of Carbon Dioxide in the water column are the major factors affecting what the current pH of a marine water column will be. They are all interrelated, and are the basis for the buffering system of seawater as well. Increasing the buffer level does not necessarily drive pH up (although it usually does). If you add large quantities of sodium bicarbonate (the common buffer additive for seawater), it should drive your final pH to around 8.2, although if alkalinity exceeds certain parameters, the buffer system will push bicarbonate out to the carbonate ion, and as the carbonate ion concentration exceeds its ability to stay in solution in the presence of Calcium ions, precipitation will occur. This may start a vicious circle in which you will then observe your Ca dropping, but the apparent value of the alkalinity will fall back to normal. The same will hold true for alkalinity if you exceed the level of Ca++ that can exist with a water columns bicarbonate/carbonate level. Under these circumstances, the excess Ca will remove the available bicarbonate until the solubility quotient of that water column drops to an acceptable level of supersaturation (between 1 to 3 or 4). This will result in a water column that displays a normal calcium, but an apparent falling alkalinity.

Also keep in mind that when corals build skeletons, they do so by depositing both Calcium and carbonate, so where does the carbonate come from?

...the alkalinity of the seawater, primarily as the bicarbonate ion (and indirectly from atmospheric CO2 and heterotrophic metabolism of CHO's).

corals remove these two substances in equimolar amounts to make skeletons, although alkalinity (bicarbonate or carbonate) may act as the proton acceptor when bicarbonate is converted to carbonate for skeletalization (and a proton is released). For the above reasons, it is very important in order to maintain supersaturation at the levels we desire for closed systems (425PPM Ca and 12 to 13 dKa alk) to first get the values established, then to supplement/replace these ions with a balanced supplement. In this manner you will be able to maintain both appropriate pH and adequate levels of Ca and Alk. Normally there is a diurnal swing in closed systems (this is normal) from a morning pH of 8.0 to an evening pH of 8.4 or so, based on the gradual consumption of free amounts of CO2 from the water column via photosynthesis. This level is at its highest at the end of the photoperiod, but gradually drops during the night as both plants and animals begin to catabolize stored CHO's for energy and release CO2 back into the water column.

As CO2 levels increase, pH drops, until the morning nadir is reached. The lights come on, and photosynthetic machinery kick back on, removing CO2 from the water column via photosynthesis and the pH starts to rise again. The buffer system is part of this, and prevents wide swings in pH during this process.

Normal and natural, occurs in shallow seas and bays, lagoons, and sea grass beds adjacent to reef areas.

If you need more details, there should be some more in-depth posts in the archives.

To address your question, increasing CO2 decreases pH, removing CO2 increases pH. Make sure your system has good circulation and adequate fresh outdoor air, either by taking a hose from outside to your skimmer's air intake, using fans, open your hood and stand doors, or open up the house whenever possible, as newer homes are quite tight to circulation and air exchange, so much so that pCO2 of some homes exceeds 450... especially if you have devices that generate CO2 (like calcium reactors, gas logs, indoor heaters that use either natural gas or similar fuels to fuel fire, etc). It may be necessary to include some type of degassing apparatus to increase the opportunity for the water column to dump CO2, especially if you have a Ca reactor. Keep in mind that pH probes need periodic maintenance, and before undertaking any drastic measures, test your probe with the borate solution, clean and calibrate your probe if needed, and keep accurate records that allow you to see trends, rather than daily data sets.

Treat the patient, not the symptoms.

hth

[graffyn]

Thanks for all the help.
So far I have only used a 2-part additive, either bionic or kent ab. I think I will try Kalk for a month or so and see how that works.

I also ran an air pump outside to pump fresh air into the sump to help with the co2 issue (new house sealed like a drum with a gas fireplace running every other day THE WIFE INSISTS so no I cannot turn it off .

Any advice on using Kalk? Which Brand? I assume I can buy a cheap kent gravity doser to top off with Kalk?

[tdwyatt]

Originally posted by graffyn
Thanks for all the help.
So far I have only used a 2-part additive, either bionic or kent ab. I think I will try Kalk for a month or so and see how that works... ...Any advice on using Kalk? Which Brand? I assume I can buy a cheap kent gravity doser to top off with Kalk?

If you're using a float switch tpo do your top off, you can raise the powerhead off the bottom of your reservoir and fill the reservoir with Kalkwasser. Let it do your topoff. You could build or purchace a Kalk reactor and use a slow pump to gradually add your top off as well.

Biggest problem with long-term use of 2 part additives is that it tends over time to skew you conservative elements, especially if you do not do regular water changes. Your Mg, SO4, etc levels will gradually fall, preventing full potential supersaturation of your water column by removing the magnesium (and other) ion(s) that would otherwise share the load of carrying the carbonate in solution. These ions normally prevent immediate flocculation of Calcium Carbonate at saturation in the presence of seed crystals. Mg also does this by contaminating the surface of the seed crystals, preventing other Ca ions from precipitating as Ca Carbonate molecules at that level of supersaturation.

Usually you can do a Mg test to determine any deficiencies due to ion dilution, and although it will not be 100% the fault of this process (the use of 2 part additives), it is a major part of it. There are very few biological sinks in aquariums for Mg, although 4% of some spp of coralline algae deposits are composed of Mg Salts. If you Mg is significantly lower than 1300 when your salinity is 35 PPT, then major water changes are in order prior to pursuing the 400PPM plus Ca levels. To simply correct the Mg level with Mg additions only exacerbates the problem that exists with the other conservative elements as well.

Lots to consider on this topic, check the archives, I know there are a TON of posts there on the use of kalk.

HTH

[graffyn]

Time for a happy update:

Following the advice of the Reef Gods, I have been dripping Kalk for about 3 weeks now and WOW what results. Wish I had been doing this all along.

Along with weekly water changes everything is perfect.

Temp: 79.6-80.4 (digital display)
Ph: 8.1-8.4 (probe)
Calc: 430 (salifert)
Alk 12 dkh (salifert)
Mag ??? (ordered salifert test kit, waiting for it)
Iodine ??? (maybe one day I will test for it)
A 0
Nitrite 0
Nitrate 0-5 (Clams enjoy just a little)


Thanks for all the advice and help.

[tdwyatt]

Graffyn, good to see that your system is doing so well, I wouldn't worry about the Mg if your Ca and Alk are at your posted levels. A Mg test kit is good to have regardless, as if your Ca and alk will not stay in the 400 and 12 range, then testing for Mag will be needed to establish your conservative element proportionality.

Great to see these results!

[cdemeritt]

. Normally there is a diurnal swing in closed systems (this is normal) from a morning pH of 8.0 to an evening pH of 8.4 or so, based on the gradual consumption of free amounts of CO2 from the water column via photosynthesis. This level is at its highest at the end of the photoperiod, but gradually drops during the night as both plants and animals begin to catabolize stored CHO's for energy and release CO2 back into the water column.

As CO2 levels increase, pH drops, until the morning nadir is reached. The lights come on, and photosynthetic machinery kick back on, removing CO2 from the water column via photosynthesis and the pH starts to rise again.


This is why I grow a large mat of chaetomorpha algea in my sump. I run a light over it when the main tank lights are out. this helps keep the ph swings down. I used chaetomorpha because it doesn't ( so I've been told) go sexual like caulerpa. I'm not sure yet how this will affect the alk or dKh as yet. but theory does hold that the ph doesn't swing as much.