Can this be right ?

[Water_Fouler]

First of all I would like to say what a wonderfull website this is! A guy at my fish store recomended that I post difficult questions here, and assured me I would get an educated answer. The pH in my 4 year old tank (30 gal.) has been running low since I purchased an RO/DI system in December. Tank pH runs around 7.9-8.1 and new salt water (Coralife salt) runs at 7.9. I drip about 1.5 gal of kalk/week and can never seem to get my calcium above 400 or my dHK above 8. I don't have a single SPS coral in the tank. Should I be doing something to the RO/DI water other than just adding salt ?

 

[Anonymous]

No need to add anyhting to RO/DI for top off, and only salt for water change. The pH is not that horrible, so leave it alone since it is fine. You don't want to Ca to be too high and 400 is fine too. Do you have decent growth of coralline algae? they do suck up ton of calcium.

 

[Water_Fouler]

My coraline growth is fair at best so I can't figure out whats grabbing up all my calcium and alk. I dose kalk, B Ionic, and Tropic Marin bio-cal. Every brand of salt I have tried has had a low pH hours after I mix it. I've tried aireation, but that only produced a modest increase in pH.

 

[Anonymous]

Water_Fouler,
:welcome:

I agree with 7e that the water doesn't seem to be terribly out of wack. Just curious, have you ever gotton a freshwater Ph kit and tested your RO water before you mix it with salt-you might be surprised at the numbers. Also, I used to aeriate the RO water for 24 hrs before I mixed in salt, and then for 24 hrs after as a matter of routine.

 

[Water_Fouler]

I have never tried the fresh water pH test, but my meter gives me a reading of 9.5 on my RO/DI water. How can RO/DI water have a pH of anything but neutral, and starting out with a pH of 9.5 how can the pH go DOWN to 7.9 after the addition of salt? :?

 

[Anonymous]

Prolly a stupid question, but when was the last time you calibrated the meter? Because the Ph of RO water is usually right around 6 or so which is why we buffer or aeriate it. Here's a snippet you may find interesting.

http://ozreef.org/content/view/115/28/

If you measure the pH of reverse osmosis (RO), or any other type of purified water, you will typically find that the pH reads around 6. This might seem like a problem to be adding something with such a low pH to a reef aquarium, but this is not an issue.

pH measurements of pure water mean very little, as all it takes is a very small impurity or additive to make a large difference in the value. The most influencial thing is carbon dioxide from the air, which adjusts the pH to in the region of 6 if left for long enough and allowed to reach equilibrium. The reason that it only takes a small additive to change the pH is the pure water has an extremely low alkalinity (which is a measure of how well the water will resist a pH change). Therefore, the lower the alkalinity the easier it is to change the pH. You can read up more on alkalinity in this Alkalinity article.

Also, this is a fab article from a series that discusses Ph and other chemistry that is a worthwhile read.

http://reefkeeping.com/issues/2007-05/rhf/index.php

 

[Water_Fouler]

It was callibrated about a week ago. I should also mention that I have been fighting what I think to be dinoflagellates for almost a year now. Apparently these damn things fair better in a low pH enviornment. I've been trying to get my pH up to 8.3-8.5 range, but it will not stay for more than a few hours. Thanks for all the suggestions guys .

 

[PezJunkie]

Just out of curiosity, I did a pH test on my RO water and it also tests out in the high 8's (the color chart for my pH test only goes up to 8.8 ). My normal tap water appears to be even higher, and the published analysis from my water company says my tap water should be ~9.1. So it appears to have dropped a little, but nowhere near 6.

I did find this article that says your RO unit may not lower the pH, depending on the contents of the feed water:

...result in a lowering of permeate pH if there is CO2 gas present in the feed water.

Usually, the pH drop is largest for waters with high amounts of alkalinity or HCO3.

When there is very little CO2, HCO3, or CO3, there is very little pH drop observed in the permeate.

Therefore it is not true that reverse osmosis filters will always reduce the pH level of water to a noticeable amount.

 

[Anonymous]

CO2 and it's relation to Ph is mentioned in the quote I posted and the article link, which is why I said "usually" and not "always"

 

[PezJunkie]

CO2 and it's relation to Ph is mentioned in the quote I posted and the article link, which is why I said "usually" and not "always"

Now you're just trying to confuse me with truth & facts. :wink:

 

[Anonymous]

Wow, a future Sumper is born :lol: . You are wasting that kind of material in the topside forums!

 

[Anonymous]

My coraline growth is fair at best so I can't figure out whats grabbing up all my calcium and alk. I dose kalk, B Ionic, and Tropic Marin bio-cal. Every brand of salt I have tried has had a low pH hours after I mix it. I've tried aireation, but that only produced a modest increase in pH.

stop dosing the kalk

on a 30-the b-ionic is plenty fine and 'powerful ' enough to meet all your tank's needs/demands-as time goes on it should very slowly raise the pH, and that can take awhile, depending on how you dose (start w/one ml to 4 gals for the 1 st week, then raise slowly if necessary, per the instructions on the bottle)

fwiw-kalkvasser can play games with your pH AND alkalinity, especially on smaller systems. if you don't use it extremely carefully/judiciously

 

[Anonymous]

RO water is typically very ion poor. Especially if it's run through a DI cartridge. Ultrapure water doesn't really have a pH. Even with good calibrated meters the pH will jump around from 3.0-9.0. It's a meaningless value and won't really tell you anything about your RO/DI water quality. For that, you should buy a TDS meter. A good quality RO/DI system will keep the TDS at 0-1 ppm.

I disagree with vitz on the use of kalkwasser, especially if you want to raise your pH. Kalkwasser is a very effective way to keep your pH high. In addition, it's very cheap and simple to dose. My 30 gallon tank gets dosed approximately 1L of saturated kalk sol'n (1/2 tsp per L) per day--every system is different of course, so you should monitor your pH frequently while you get an idea how it affects your tank.

 

[Anonymous]

kalkvasser is also a very easy way to completely crash the alkalinity in your tank, if it's used improperly, or without experience

without knowing the strength of the guy's kalk mix, and combined with his ALSO using b-ionic-sounds to me like someone who's either 'additive happy' or inexperienced

ime/imo, b-ionic is MUCH safer and far less risky an additive system than kalkvasser is, and supplements more things back that invert life take up than kalk does-i've always found it to be far superior for increasing coralline growth rates than kalk

i'd be far more concerned with maintaing a good alk/Ca/Mag ration than i'd be about pH-i've had tanks run at 7.8 with beautiful healthy corals/inverts, and seen tanks/sytems with even slightly lower than that pH level that weree beautiful and healthy-plus if the ratios are kept correctly, and other issues are up to snuff-the pH will usually slowly drift to a higher range anyway

it could be that the poster is also testing their pH at the low end of the daily ph cycle

 

[Anonymous]

and btw, b-ionic is extremely cost effective for tanks 30 gallons or thereabouts in size

 

[ChrisRD]

I agree that kalkwasser needs to be used with caution (especially in smaller tanks) due to its ability to raise pH so quickly. I also agree that a two-part like B-ionic is all you should need to maintain your numbers and is an ideal solution in a small tank like a 30. IMO the kalk is an excellent solution too - just requires a bit more caution.

As for kalk causing any sort of alkalinity "crash", in 10+ years of using it in my own tanks I've never experienced such a thing. I've also used it in combination with B-ionic as well as a Ca reactor (when kalk alone wasn't enough to maintain Ca/alk levels) and, again, never experienced any problems.

IMO the numbers mentioned by the original poster are fine. Personally I would go with a simpler supplimentaton routine, but whatever works for ya. :wink: If it were my system and I wanted to raise pH a bit (and I was sure it wasn't one of the common low pH problems that needed correcting) I would just up the kalk dosing slightly.

Article from Randy Holmes-Farley on low pH causes/cures that might help:
http://reefkeeping.com/issues/2004-09/rhf/index.php

JMO/JME of course...