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FAQs on Marine pH, Alkalinity, Importance

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: 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: Science, pH Measure/Test Gear, pH Controllers & pH Buffers/Buffering, pH Anomalies (Troubleshooting/Fixing), & pH Products by Name, Manufacturer, & Marine Supplements 2

You want a relatively stable, "high" pH... 8.1-8.4 is ideal... especially not fluctuating more than a few 0.1's in a day's time.

Basic Questions: Measures of water quality, value     4/16/14
How's it, Bob?
<Fine, thanks>
I was at my local LFS the other day, and inquired about ORP and PH. He has some pretty darn nice displays, and probably has the best looking coral selection in the state. He seems to know his stuff, however I became
confused during our convo.
When I asked about measuring ORP and PH, he stated to me those were useless.

He said to me the PH in seawater is set to stay at a given PH, and measuring it will only lead people to chase the perfect ph by adding buffers that will throw off other elements. He told me in a reef tank, the two things to measure are Alkalinity and Calcium, and if those are good, your PH will be in line as well.
<Interesting point of view... I myself am much more a bigger fan of measuring alkalinity than pH... but both can be useful windows; provide views into water quality, changes>
He then showed me his reef set ups, and stated there were no PH monitors nor ORP.
Could this be remotely correct? I have always read you had to monitor them, however hearing this from him, has me puzzled. Says the only time he measures PH is during freshwater dips.
<You can easily search, read my opinions on these... even just on WWM.
RedOx is a supremely important and useful measure... ALL public aquariums utilize O3... Most all marine wholesalers, the collecting stations I've had a hand in devising. B>

pH. Natural SW coll., use      2/8/13
Hi Crew, This is really feedback for your readers. Having read over the years that pH should be 8.2 to 8.4 I am surprised that the seawater where I stay on the Andaman Ocean (Indian Ocean) is 8.0
<Collected where? You may have to get a bit offshore, the open sea. This being stated, 8.0 isn't too low for most all uses; as long as there is sufficient alkalinity/buffering capacity to insure against drastic drops>
I was concerned that my tank which is inverts and fish is too low. I have checked it with two test kits, API and Tetra. The water I take has delicate fish like the Moorish Idol nearby
<Not delicate in the wild>
 and I don't take it if there has been any rain in the last few days leading to potential runoff from the land and always at night in case swimmers etc have used suncream etc and away from any small fishing boats.
I hope this helps your readers. Regards, Adam.
<Thank you for sharing. Bob Fenner>

Alkalinity pH question 3/26/12
Hi there again,
<Hello Abbasali>
Small question. Background: I run a FOWLRI tank. I dose Kalk as top up once a week for Ca and drip a NaH2CO3 solution once a week to bring the Alkalinity to 9-10 degrees. However by the end of the week it's back at 8.
Calcium remains at/around 400 - 450ppm. pH runs from 8.0 in the morning to 8.3 just before lights out.
Within a week however the pH tends to be around 8.0 and Alkalinity around 8 degrees while calcium remains somewhat the same if a little lower.
<Nothing wrong with those figures.>
I would like to have my alkalinity a little high since my coralline grows better.
What could be the reason for this?
<Acids in the water, excess nutrients, overstocking.>
Note, the tank is heavily populated with shrimp (at least 8 individuals)
and has an ATS in addition to skimming/RDSB.
Tank specifications are
DT Vol. 55g (48x18x15)
sump 25g
P 0
NO3 0
Please let me know.
<I see nothing wrong here.  I keep my dKH at 8 and coralline grows just fine.>
<You're welcome.  James (Salty Dog)>

Pulsatory function in Xeniids- low pH 6/11/03 Hi Anthony - Upon further checking it does appear that my PH is falling too low at night.  Looks to be around 8.0 and 8.1 in the morning before lights come on.   <yikes... yes, too low for some finicky corals like Xenia sp> I'm using Seachem Marine Buffer (supposed to maintain ph at 8.3) in conjunction with baking soda. <actually... these products do not have the ability alone to raise you any higher than 8.3. Do supplement with Kalkwasser at night> I've also been keeping the sump lit (15w fluorescent light) on an alternate lighting schedule thinking that this would level out the day/night swings in ph.   <some help yes> What else can I do to keep the ph at or above 8.3 and stable? <definitely Kalkwasser dosing after the lights go off... tried and true! Archive my "Kalkwasser slurry" method here on WWM in the archives or peep it in my Book of Coral Propagation if you have access to a copy> thanks again, Bryan <best regards, Anthony>

Re: thank you 5/20/03 Thank you so much for replying and helping me :) I appreciate it so much, not many people reply when I have important questions. <always welcome, my friend> I have one more question, Corals like relatively high pH, <all marines in general favor high and stable pH especially... a steady target of 8.3 (day and night) might be a fair goal> and require so much for their growth that I couldn't begin to address it here <do focus on stability more than high-end ideals for the given ranges of chemistry and bio-minerals. Kind regards, Anthony>

High pH in seahorse tanks?!   2/9/06 Hello WWM crew:)  I have a concern that I would like to run by you.  Though I have never really had a problem of this nature in the past, it seems as though my luck has run out.  I recently tested the pH of my three dwarf seahorse tanks, and the results were completely different for each of the three tanks- 8.2, 8.4 and 8.7.  I know the first two values are acceptable, but the 8.7 is concerning me, especially since it is a juvenile tank.  I have not seen any ill effects as of yet, but I know that value is well beyond the normal range these animals are accustomed to.  Any ideas as to what I can look into? <... what is different about this last system? Substrate, use of ozone, UV?... water treatments?> I tested the KH for all three, and all of the tanks tested between 9-10 dKH, so I know this is not being caused by excessive alkalinity.  I have not added any calcium or other mineral supplements at all as well...so I am a bit baffled.  I would not say there is an excess of photosynthetic activity either, and I am not overly aerating the tanks.  Any ideas? Thanks again,   D Conners <Mmm, I would not be overly concerned here... there is a good deal of physiological adaptation (esp. over time) re pH and most marine fish groups... Bob Fenner>

pH alk? I have a few questions on pH and alk. I've seen in different books that dKH should be between 7-10 and also 12-18. which is correct?  <8-12 dKH is safe and healthy IMO. Closer to 8 if you run a high calcium level (over 425ppm). ALK over 12 dKH is dangerous (crystalline precip) and only recommended for hardcore coral growers that test water daily and have many scleractinians. Most people will have problems with such a high ALK in time> my problem is... my dKH is 16-17. my calcium is low, like around 300.  <typical... neither can easily or safely be at the high/max end. Still... the tank would be better off around 10dKH and 400ppm> my pH is around 8.0-8.2, but will drop without the addition of SeaChem marine buffer to 7.8ish within 48 hours.  <a lack of aeration (not circulation) may be indicated here (accumulated CO2). Aerate a glass of aquarium water vigorously with an airstone and see if the pH rises after 12 hours. If so... you have a CO2/aeration problem.> how can I raise the pH without increasing the alk? <Kalkwasser> my alk is so high right now that I can't seem to increase the calcium without clouding my tank.  <exactly... a crystalline precip. Do several large water changes to dilute this imbalance then add Kalk and buffer as necessary> also, why would the pH drop like that if the alk is high?  <many reasons... CO2 being one of them> I have a 50g breeder w/ 50lbs LR, and few snails and hermits and some polyps. no fish yet and I'm not feeding anything. 20g sump w/ skimmer that needs to be emptied every 3rd day. all other readings are where they should be. thanks, Neil <best regards, Anthony>

pH swings Hey Bob, I recently bought a PH monitor for my 30gal reef. I have been monitoring the PH level which seems to be fluctuating a little too much. In the morning the monitor reads around 7.7-7.8 and then at night it reads about 8.1-8.2. Is this fluctuation something I should worry about, or is this spread a normal reaction to day and night characteristics?  <A more than natural than not cyclicity... I wouldn't worry unless your alkalinity was low... like less than 3.5 millieq./l> I starting dosing Kalkwasser to see if this would help stabilize and raise the PH a little better. I have heard that large PH swings are due to low alkalinity, is this true?? <Oh, yes... gotta start reading all the queries ahead of responding...> Should I add a buffer in addition to the Kalkwasser? If so, should I only add it when the alkalinity is at a certain level, or is it safe to add it maybe once a week?  Thanks for the help Bob, Patrick >> <Okay, now HAVE read the whole missal... yes, good idea to check, augment alkalinity along with use of "supplements" such as Kalkwasser... YOU need both alkaline reserve AND biominerals... one w/o the other is not only worthless, but dangerous to your captive life... Many approaches to this question... Maybe take a read through the materials on these issues posted at my site: www.wetwebmedia.com and get back to me if you're unsure of how to proceed... Bob Fenner>

I need help please!!!! I have a 55 gallon marine tank which has been set up for 3 weeks now. I have one damsel in there, and since my nitrite and ammonia were practically at zero I added a Bursa trigger in there. Yesterday, I saw the fish looking very stressed and near death. I tested all components of  the water and they all checked out ok. Except, the PH had dropped to around 7. I did a 25% water change, and added two air pumps into the tank. I also added a marine buffer. Is there anything else I can do to bring the PH back up? What causes this dramatic drop? Thank you >> The pH dropped to 7 even? This IS low... and a cause for concern... does this tank have a lot of dead, dying live rock? No buffering gravel... What brand of salt mix did you use? Or natural seawater?... You need to bring the pH back up,,, but not all at once... and you need to understand the concept of alkalinity/alkaline reserve.... Do read over the pieces on these topics (pH, alkalinity) about marine systems stored on the web site: www.wetwebmedia.com and we'll talk when you can answer back. Bob Fenner

pH too high (maybe, but why...) Mr Fenner- Hello again. I mailed you a couple of days ago about controlling Caulerpa racemosa in my 55 gallon reef tank. Thank you for the advice. I have another concern. That is the pH of the tank. It used to run about 8.3 which from what I understand is about as high as is should be allowed to get. But the Alk was only about 1.7, still everything was OK. I have been trying to raise the calcium levels by adding the Bionic two part solution and I have noticed my pH seems to be rising (which the bottle warns of). It is probably around 8.4 now (kind of hard to tell on those charts, they jump from 8.2 to 8.6 - 8.8). So I started to look at some other calcium treatments. It looks like they all have the potential to raise pH. I really do need to raise the calcium level. It is testing around 300 and should be 400-450 according to what I have read.  <Yikes... a bunch to state here... for one, you need a better (more accurate) test method for pH... and two, alkalinity, calcium and pH... do you understand how these are related? I wouldn't become overly concerned either about the transient rises in pH... or the 300 ppm reading for free calcium in your water... You do want to elevate both alkalinity AND calcium together... Please read over the sections posted on our site: www.WetWebMedia.com on these qualities> I know there are additives to lower pH. Would you recommend trying one of those. <No. Not needed or desirable> I don't want to overshoot and end up too low! I do a 3 gallon water change every week but it doesn't seem to make much of a dent in the problem. Any ideas on how to address this or am I worrying about nothing?  <Mostly the latter...> By the way, a few stats on the tank might help out... tank has been up about four months 55 gallons approx 80 lbs of white base rock approx 45 lbs of live rock about 2-1/2" of aragonite crushed/sand mix Yellow Tang Firefish lots of hermits and snails two cleaner shrimp two peppermint shrimp two small corals (the dealer called them Flowerpots one of which is doing great the other could be better) two powerheads two Emperor 400 power filters more fish to come... clown(s), blennies or mandarin... Thanks again for any advice you can provide. Greg <Take the long term view here... and just use the two part B-ionic product as labeled... and not worry. Bob Fenner>

Another high pH question Thanks for your prompt response! <You are welcome> So it sounds like I shouldn't be concerned about the pH being up to 8.7?  <Not much... this will come down with time> I know that some invertebrates are particularly sensitive to pH. Is this only if its fluctuating or just if it varies too far from the norm? <Mmm, both> I would like to keep a brittle star, peppermint shrimp, cleaner shrimp as well as feather dusters (and a scooter blenny) eventually in with the horses. All of these would be OK with that kind of pH?  <Better to wait for it to drift down to 8.5 range... do you have an alkalinity test kit? Please do read over the marine alkalinity AND pH sections posted on WetWebMedia.com> I currently have some Nassarius and Cerith snails as well as a few Red Leg Hermits. Merry Christmas and thanks for all your help! Penny <A pleasure my friend. Bob Fenner>

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