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FAQs on Marine pH, Alkalinity, Measure, Test Gear

Related Articles: pH, Alkalinity, Marine Alkalinity, Synthetic or Natural Seawater, Water Changes/Changing, Understanding Calcium & Alkalinity, The Use of Kalkwasser by Russell Schultz,

Related FAQs: Test Gear: Rationale, Selection, Use, Troubleshooting, Testing Methods: Liquid Reagent/Colorimetric, Dry Reagent Test/ing, "Paper", Titrametric, Electronic & About Brands/Manufacturers, & Marine pH, Alkalinity 1, Marine pH, Alkalinity 2, Marine pH, Alkalinity 3Marine pH/Alkalinity 4, Marine pH 5, Marine pH 6, Marine pH 7, Marine pH 8, & FAQs on pH: Importance, Science, pH Controllers & pH Buffers/Buffering, pH Anomalies (Troubleshooting/Fixing), & pH Products by Name, Manufacturer, & Marine Supplements 2

Simple colorimetric assays are almost always fine... There are titrametric means... even electronic. I would not use paper/test strip types if there is a real question of what your pH is.

pH Monitor Question 6/12/10
Hi there Crew!
Quick question for ya... I bought a Hanna Gro-Chek continuous pH monitor, and would like to use it in my nanoreef tank, but am concerned that the temperature and grounding probe is stainless steel. Is this going to corrode (probably, right?), if so, how fast, and what can I do to prevent or slow it? Will wiping down the probe periodically help? Or should I return it and exchange it for another monitor (pinpoint, etc)?
I believe this particular monitor is designed more for hydroponic applications, but is cross-listed in the aquarium and aquaponic section of Hanna's website. The electrode is encased in plastic, so that should be fine... just worried about the ground probe. Any thoughts?
<I'd check with Hanna. There are different grades of stainless steel and the better/purer grades will not deteriorate in salt water. Is possible that for horticultural use, the grade of stainless used may not be resistant to saltwater long term.>
Thanks as
always for your advice!
<You're welcome. James (Salty Dog)>

Ph/Alkalinity? Water Quality Testing   4/17/2010
<Hi Dawn.>
I just want to say how "Wonderful" your site is.
<Thank you.>
My question is about Ph/Alkalinity.
I have a 150 gallon tank which consists of fish, LR, anemones, starfish and a few urchins.
I test for PH, Ammonia, Nitrate and Nitrite. I have not tested for alkalinity.
<Always a good thing to test for.>
The other day I got a bottle of test strips you just "dip" in and read.
<Unfortunately, the dip strips are notoriously inaccurate.>
Upon reading this, all my tests were fine except the alkalinity.
On the bottle the color chart is green, whereas my test strip was blue!
<I rest my case.....>
Is this a test I should be testing?
If so, I would need an alkalinity test. Now an alkalinity test and a KH test are one the same, correct?
<Long story short, yes.>
Would my alkalinity be that far off even if my PH test reads 8.4?
<It can be. A grossly oversimplified 10 words or less definition of alkalinity is the ability of the water to resist a downward shift in pH. so the first sign your alkalinity is too low would be fluctuations in your pH.>
If I am understanding this right, the PH and alkalinity work together.
<They work together, but they are not the same thing.>
Without a test kit, I am guessing my alkalinity is too high.
<Not necessarily.>
What would I do to lower it to a safe level?
<First you need to test it. - get a good KH test kit - API makes one that is only about $5.00 in a pet store.>
I use marine buffer to raise my PH, which I have read on your site you can use baking soda (1 tsp. per 50 gallons).
<The buffer is also boosting your alkalinity. Do have a read here. http://www.wetwebmedia.com/alkalinity.htm >
One quick question about foods, when you talk about buying seafood at the local grocery store you are talking about "fresh" not "frozen" correct?
<Either will be fine. Though usually the frozen is a bit less expensive..
<My pleasure.>

Re pH/Alkalinity? Water Quality Testing 4/19/2010
This is in reference to the PH/Alkalinity.
<Hi Dawn.>
I purchased the API KH Test as you advised. It took 20 drops to turn my water yellow!
<Alkalinity is very high. dKH of 20.>
If I multiply the 20 drops by 17.9 as per directions that equals 358 ppm..
It should read 89-125? I understand to increase the KH I would use API Buffer Max Marine, or as per your site baking soda?
Could you advise me on how to decrease this level and to why it would get so high?
<Stop adding any buffer. Regular water changes without buffer will start bringing it down.>
<Just do it slowly and gradually. Do not add any calcium supplements until the alkalinity goes down.>
Will this level harm the fish?
<As long as the pH remains stable, no.>
My PH test reads 8.4.
Thank You Again,
<My pleasure>

Re Re Please Help/ Tridacna Clam Health/Predators/Now Low pH 3/18/10-3/19/10-3/22/10 - 4/1/10
I think I may have found my problem. I had ordered some new Salifert test kits, and the cal, Alk matched compared to the original Salifert I had. Then I tested the pH. I was shocked, 7.6 after about 4 hours of lights being on. Checked it with my original Salifert it was 8.1. Had pH probe shipped out, HM digital and ph is at 7.87 about 5 hours into light cycle. I remember reading an article while having this problem with my cal and Alk about precipitation at different pH values. I ask you to bare with me and please help. I know I have to find the cause of this low pH. In the mean time what in your opinion is the best and safest way to start my increase.
<First, what is your NO3 reading and be sure you are not reading N, total nitrogen. High dissolved nutrient levels (nitrates) can drive pH downward and is generally caused by overstocking/feeding and/or poor maintenance
practices. Do you run an efficient protein skimmer in the system?>
Thanks once again,
<You're welcome. James (Salty Dog)>
Re Please Help/ Tridacna Clam Health/Predators/Now Low pH 3/18/10-3/19/10-3/22/10 - 4/1/10 - 4/2/10
Nitrates tested zero. It is the stock skimmer for the Cadlights 39 gal pro. Just ordered a bubble magus which is supposed to be a big improvement.
<Craig, all found here and related articles/FAQ's. http://www.wetwebmedia.com/marphalk.htm
James (Salty Dog)>

pH Meter or Pen? -- 02/13/10
Hello all,
<<Greetings Whit>>
Thanks again in advance for your help!
<<Is our pleasure>>
I'm debating between purchasing a pH meter with continuous readout vs. the pen style, and I was wondering the pros/cons for both.
<<Hmm'¦ Accuracy, ability to calibrate/adjust/replace probe versus portability, price'¦>>
I have a continuous meter now, but from my experience, the probes need to be replaced and re-calibrated frequently.
<<Indeed'¦but this also insures accuracy>>
Is this the case with the pen meters? Do they require much less maintenance?
<<I seem to recall one such pen-type meter for which that could 'replace' the probe'¦but for the vast majority this is not the case. Once these pen-type meters no longer take/hold an accurate reading (as validated with a reference fluid), you have little option but to replace them. The up-side of this I suppose, is that you can obtain some of the pen-type meters for the same price, or less in some cases, than the cost of a replacement probe for the continuous-readout type meter. However, in my admittedly limited experience with pen-type meters, I feel these are less accurate/reliable than the alternative'¦at least for 'any in the same price range' as a replacement probe for my continuous readout unit>>
Thanks again!
<<Happy to share'¦ EricR>> 

Re: Help! My tank looks like a plantation! Now e- pH measure...  -- 08/01/07 Thanks Bob. Previous to the disaster, the parameters seemed perfect. I was using a Pinpoint Ph monitor and the new probe is faulty (says me). <Mmm, unusual... perhaps just needs to be calibrated... Otherwise I'd return> I overdosed the tank with buffer which pretty much caused disaster. <... please see WWM... All such changes need to be made gradually VIA pre-made/mixed water> I contacted the manufacturer, he told me there's no such thing as a reliable Ph test <What? Ridiculous> which makes me wonder why I bother with the Ph monitor if it's not reliable despite the promise that it is. <These tools are accurate and precise...> I should probably get some more snails. I haven't seen the Nassarius for a bit. Thanks so much again, Lisa <Keep reading. RMF>

Re: Was: Help! My tank looks like a plantation! pH probe. -- 08/01/07 I calibrated it twice when it seemed to be reading low after the first week. Is it possible the calibration fluid is bad? I'm using the packets 7 and 4. <Not likely... I think you have a bad probe... Perhaps a manufacture defect, broken or let dry out too much... Time to send it back. BobF> Thanks, Lisa

pH Issues'¦The Need For More 'Understanding' -- 07/01/07 Hello, <<Greetings>> In a previous email, I was recently advised regarding my Nitrate problems and want to say thanks for the help. <<Don't know who this was, but am sure you are most welcome>> My Nitrate is around 20-30 ppm and improving each time I check. <<Ah good, but still a ways to go>> It is easy for me to maintain now with partial water changes...that darn wet/dry was the culprit. <<These devices serve a purpose, but I agree this is often the case>> Anyhow, my next and maybe even more important problem is my pH levels. <<Oh?>> It is always low. <<Mmm'¦>> I use RO/DI water with Red Sea or Oceanic salt. <<I would use a better/more consistent mix'¦perhaps Seachem'¦or Tropic Marin if you can afford such>> Recently, I've been using Kent Marine "Liquid Calcium Reactor" for buffering new water added, but not the whole main tank though. <<Again, I suggest you abandon this product and try one actually formulated to boost/maintain pH. Seachem's Reef Buffer is such a product. (are we starting to see a trend here? [grin])>> I have even added small amounts of baking soda, (about 3 teaspoons dissolved at one time) but this does not seem to be helping. <<The Sodium Bicarbonate will help bolster Alkalinity but really does little for boosting pH; it contains CO2 as a byproduct of its manufacture. I've even seen pH fall from the addition of large amounts of Baking Soda. Driving-out the CO2 from the Baking Soda will render Sodium Carbonate, which 'will' raise pH but requires careful use not to overdue. If you wish to give this a try'¦spread the Baking Soda on a cookie sheet and 'bake' in the oven at 300-degrees F for about an hour. Or save yourself the time and possible grief and use the Seachem product. I've found you can even save a little money by mixing Baking Soda with the Reef Buffer on a 3 to 1 ratio and still attain satisfactory results>> I try to be cautious to change things in a slow manner, not abruptly. <<Sage advice in most instances>> My tank is a 160-gallon FOWLR tank with about 19 small to medium fishes, 120-lbs of live rock, and around a 4-inch aragonite sand bed. Last but not least, just before writing I took a pH reading of around 7.4 and a 9.6 dKH on alkalinity/hardness. <<Hmm'¦how are you measuring pH (meter, test kit, strips)? I would validate this test as I think a true pH of 7.4 would be having a deleterious effect on your fishes>> I think my buffering is ok, but not the pH, obviously. <<Maybe, maybe not'¦validate that test with another/newer test kits or a borrowed meter>> Is there anything you can suggest based upon this information? <<As already stated>> This is a new area for me. <<Ah yes, well'¦you need a bit more understanding of the topic. Start reading here and among the links in blue: http://www.wetwebmedia.com/marphalk.htm >> Let me know if you need any more information. Have a nice day. Christopher <<And you as well. EricR>>

pH measurement variation, Electronic  2/18/07 Great site guys - I'm a month into a 44 gal (US) tank, just two clownfish, cleanup crew and live rock. I use an electronic pH monitor, and wanted to share an unusual source of error. <Okay> One afternoon the pH (normally around 8.15) was reading 7.94. I nearly started to add lots of Kalk, but I was puzzled how that much water could change that fast. It hadn't - one of my snails had crawled down the electrode, and slimed it through the plastic outer shield. Once he was gone, normal readings were restored... <Interesting> Now if the pH electrode had been on a controller wired to the Kalk pump, I dread to think what could have happened. I'm still thinking how to make a snail guard to keep them far from the actual glass bulb. <A good idea> Oh, for those folks asking after pH standards, my vote is for Omega pHydrion kit - 3 lots of 10 powder capsules (pH 4, 7, 10), all for £15. <Thank you for this "plug"> Each make 100 ml, with 3 month shelf life.  If you really want to make your own (or just to check the calibration has worked), the easiest is 0.01M borax at pH 9.18, but check the temperature, and it goes off with CO2 in the air, so make it fresh. <Ah, yes> National Bureau of Standards has good info on buffers - sadly I can't see one around pH 7 from kitchen materials. <Very pure water...> Thanks --David <Bob Fenner>

Lighting interference with pocket pH tester   1/12/06 Belated Happy New Year! <Thanks> I thought I would pass on an experience I have had recently that cost me dearly. I bought a Milwaukee pH tester, waterproof, very nice. Next I bought a new Jebo pc fixture with 2 65W half 10000K and half actinic lamps. This fixture has an external ballast which is very nice, lighter in weight and easier to hang above the tank. Now for the bad part. When I used my new tester on my tanks, I have 2, it read perfectly, 8.2 to 8.3 on each tank. Before I checked my pH levels again I bought the new light and was using it. On my smaller tank the pH was still 8.2 to 8.3 but my big tank was 6.9!! I panicked and got some buffer and started trying to get the pH up. Nothing was working. I don't know how much I finally ended up adding but I couldn't get the pH above 7.3. Hindsight being 20/20, I realize how big a mistake I made and won't repeat it. But I didn't find out what was the problem until I tried  to show a friend the way the pH tester worked and had it in a cup of water and turned on. It was reading 7.2 in the cup but when I brought the cup up to the top of the tank to test the water there the reading dropped to 5.4! I moved the cup with the tester in it back and forth a few times and watched the reading go up and down. Finally I turned the Jebo light off and the reading stayed put. And it tested the same as the test kit showed. I never thought about a light fixture interfering with a tester. <Mmm... RF... electronics...> Unfortunately I didn't learn until after I burned up most everything in my tank with high pH, 8.8 was the highest it tested. And of course then I started doing water changes and everything I could think of to bring it back down. It seemed to take forever to stabilize. I lost all of my 'pods, some snails, my serpent star, and cleaner shrimp which had gotten so big. I was heart broken for I don't know how long. The good news is that after what has seemed like forever my tank is back healthy. Even my 'pods are back and I have baby Nassarius snails too. They look really cute in there. I am still dealing with algae problems like a newly cycled tank but it's getting better. I am telling all of this to hopefully keep someone else from having a similar disaster. Agnes <Mmm, Please do consider writing Jebo re this interference issue... Could be very important to their business... especially when the folks at UL catch up with this part of the trade again. Bob Fenner>

Test Kits? Hi Bob, Thanks for the info on test kits, and for the baking soda suggestion. I'm in the process of adding it (didn't want to add it all at once, so I'm doing it over three days). Follow up question: Would it help further if I also added some sodium carbonate, or will the bicarb reach equilibrium as a bicarb/carbonate mixture on it's own? Perhaps I could mix up a stock buffer solution, and add when I add my Kalkwasser... Any dangers here? Thanks again, Randi <Very perceptive on the carbonate/bicarbonate question... Yes, just add the bicarbonate... it would turn (more to) carbonate in a more alkaline environment... And some dangers in mixing Kalkwasser and the bicarb... best to settle on some of both... and a "mid-ground" in alkalinity and biomineral concentration... Nothing wrong with 350ppm calcium with 3.5 or higher alkalinity... 400-500 ppm calcium with low alkalinity is worthless... Add the materials separately... IMO... or buy a pre-made dry mix of the two and mix/add it at once... or best... look into a calcium reactor... I see one in your future... and you're happy... Hmm, I would send those test kits back... sounds like the reagents have had it... I mainly use Hach and Salifert test kits... fast, accurate, and inexpensive considering we do many tests...  Coralline algae can/does spread quickly given propitious circumstances: plenty of biominerals, high alkalinity (3.5+) and a paucity of competing and predatory life forms... it can cover an entire system in a month at about the best...  Hmm, do me a favor, and add a few teaspoons to your tank (about one per ten gallons) of baking soda (sodium bicarbonate) and check in the morning to see if you can register any alkalinity...  Bob Fenner >>

pH Monitors Hi Bob, Santa Claus is coming to town, and I was thinking of asking him for a pH Monitor. They seem very useful, but are they more trouble than they're worth, i.e.; will I have to constantly have to re-calibrate it, buy a new probe every x months? Any input on these "gadgets" would be greatly appreciated. <Is this for linking to a specific controller? Or just a time to time "pen type"? If the former, look to the manufacturer's recommendations. The latter? Most all the inexpensive models are fine... For new purchase of the former I like PinPoint... the latter? I use a YSI (Yellow Springs Instruments) And nah to having to recalibrate them if they're stored properly (moist, in standard solution) or buy new ones all the time... they last for years if properly cared for.> LEAK UPDATE I month ago I wrote you about a leak in my tank. After writing to you, I talked to my LPS and asked him if he had any advice. He showed me one of his tanks that cracked right in front. He put a piece of cellophane tape over the crack, then put some silicone sealant over the tape. He said it was there for a year now. As my leak was coming from under the tank frame, I figured I'd give it a shot. (much better than tearing down the whole tank). I'm happy to say it seems to be holding. My leak was very minute, actual water drops never reached the bottom of my tank stand. I got a "growth" of salt creep which was manageable. So, one would want to consider that before trying this. Have you ever seen any one use this quick fix? If you have any comments on this I'd appreciate it. <Have seen it... and done such things myself... as you can appreciate, not a good suggestion to post on the Net... Would/do encourage the resealing if this tank at your earliest convenience... and investigation as to the cause of the leak (likely an uneven surface the tank is on...)> Thanks as always for your help, and have a Happy Holiday, Tony <You're welcome my friend in fish. Bob Fenner>

pH Monitors Dear Bob, I'm looking at the Pinpoint monitor. I'm not planning on connecting it to a controller. I was under the impression that these monitors were left in the sump at all times as a constant pH monitor.  <Some, yes... other electronic pH meters are intended for periodic use... still others are utilized with pumps/valves to feed materials into a system to modify the pH.> My thinking was that as pH is arguably the first sign of things going bad (or good), it would make my life easier by not having to do a standard test all the time. Please educate me... <The first sign? Likely your animals' behavior/appearance... But pH is a useful window for "slower", "longer-term" changes... Some diurnal pH fluctuation is to be expected, and the reductive events in a captive system will trend pH downward... but you can have entire wipeouts without a shift in detectable pH...> ...and YES to not posting that (leak remedy) on the web. I could see it now, someone trying to seal up a dripping leak with Scotch tape. YIKES! I'm going to see if the method holds. Tearing down a tank is the pits..... <Ah, glad to find we're in agreement> Thanks again, Tony PS Just a note, my son (13) recently set up his first FO 29 gal. tank. Now, he's using your book (CMA) for a reference. He loves it, too. His filtration is an undergravel filter... that all. He's got a damsel in the tank now. He plans on getting only hardy fish (Dotty's, triggers, etc.) If you could add only one of the following (Skimmer, canister filter, fluidized bed) which would be the most beneficial. His budget is meager at best. I help him out, but, want to teach him to save a little dough for the things he wants. <All worthwhile lessons. The skimmer is my first choice... maybe the less-expensive new "Prizm" by Red Sea... Bob Fenner>

Re: pH Monitors Thanks again, Bob. Two more and I'll leave you alone.... 1 - Are the Pinpoint monitors supposed to remain in sump all the times? <They can (but do take out the electrodes for periodic cleaning) or can be utilized periodically... like moved between tanks for measuring, then stored... I would do the latter.> 2 - Is the prism skimmer quiet? I've got a Turboflotor. How quiet is it compared to the Turboflotor? <Only have second hand experience here, but yes, are much quieter> Thanks again for all your help, Tony PS The web site gets better all time, keep up the good work! <You're welcome. Thank you. Bob Fenner>

pH/Reactor Advice II Hi Steve: It turns out that the brand new pH test kit that I bought with an expiration date of 2005 was defective! I mean this kit was brand spanking new. Absolutely amazing. My pH was most likely around 8.1 all along knowing what I know now. It is now around 8.2 mornings/8.4 evenings because I started to add buffer to correct my false low pH before I figured out what was going on. There's a lesson there for me and anyone else reading this. Just by coincidence, FFExpress is having a sale on pH meters -- very cheap compared to $1,500 in livestock. Sorry to bother you, and elated to know that my tank is doing much, much better than I first feared. <No bother at all. Glad to hear things are OK. Do remember to get the reagents to calibrate the pH meter if you get one.> As for the Ca reactor, I need to play with it some more to get a better handle how it performs and its sensitivity. It's only been two weeks. I was just trying to see if I could get any additional input from you while trying to dial it in. <Now rereading your first query, you seem to be pretty close at 20 bubbles per minute. A little more tinkering and you should be set.> I will never use the Chemi-clean again. Felt very funny/leery using it the first time because it goes against everything you guys preach. Cyanobacteria came back anyways, probably because I only used a half dose of the stuff originally. Either that or the stuff is snake oil. <Probably the half dosage. Most of these Cyano killers are erythromycin and it will kill Cyanobacteria as well as some other things and turn your tank a funky color a lot of times. But does nothing to stop it from coming back later.> Very small bloom right now. Will try to correct with reduced lighting, water changes, good feeding practices, perhaps macro-algae... <A good course of action except for the reduced lighting. Your corals need their light.> Thanks again for your ear and your wonderful service. Jim <Do not hesitate to write again. -Steven Pro>

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