Tested pH with lab pH meter and it's 7.5!

[KonradTO]

Check your salinity, something is not right, most likely a testing error or salinity is off, but your salinity would have to be crazy low to be 4 dkh off.

I think the evaporation will be less than you think, my tank is 14g with a mesh lid, maybe 500ml evaporation a day. Boiling the kettle or taking a bath/shower would put much more moisture into the room than a small tank.

Yeah I am at 33.5 ppm. I am aiming for 35 but as you said that does not explain such drop in kH..

 

[Adam1985]

Wow thanks for the detailed answer!

Happy to help!

True. I unfortunately had too much of dinos at the moment (they started growing on my porcelain crab too !!). I must say that after yesterday I installed the UV light and cut all the macros overgrown with dinos, the situation now looks much better. I covered the tank with towels and turned off all my lights. For now it seems clean but I know its too early to decide if it worked.

It sounds like a good decision what you did here. I personally think UVs are underutilized but don’t really believe in 24/7 use as they have their drawbacks as well. On my personal tank I keep mine hooked up but off unless I have an issue. But on the rare occasions it’s needed , it’s a good tool



As with any organism, if you don’t want to propagate you’ve got to either neutralize it or cut off its food supply. Sounds like you did a good combo here. Looking forward to a hopefully positive turnout.

Yes I usually do this weekly. My problem was that with my test kit for pH, for example, I was sure I had ph 8, but apparently the test was not that accurate. I also found out that if I use my pipette for measuring the water for the test it differs from the vials provided by the test brand (sera). Basically they say "fill until 5ml mark" but its not really 5ml. This had me testing for weeks in the wrong way probably.
I tested today pH at my lfs but I think that- their pH probe is not working well. Was giving pH 7.1 and all the other probes in the lab are on 7.6-7.7 range. I get basically 3 different measures from 3 different probes

Sorry to hear about your testing challenges. I’ve experienced the same issues personally until I just f got better equipment or stopped testing, depending on the parameters and over time for cost reasons.

Even Hanna, which is great, isn’t so consistent with the markings on their vials. I measure all my samples using syringes or pipettes.

I think the general consensus is that pH meters are the most accurate way to measure pH, but their calibration and maintenance are critical and probes’ lifespans are finite. Might be worth asking when theirs have been calibrated and replaced. Some businesses will sacrifice result quality in lieu of less frequent maintenance/replacement.
We’ve had a lot of advances in the past 20 years as far as understanding aquarium chemistry and how things work, but poor data quality with testing coupled with our knowledge is still now biggest issue. I think we generally test too much and don’t always consider the quality of the test results before taking action on them.

Yes this sounds like a good idea. I actually was reducing WC to increase my N and P, but since I can dose now I could try with this.

I hate WCs as much as anyone, but for some purposes they really are the best option. On my own tank I’m trying to generally reduce WCs over time because I don’t like doing
but if anything goes south or gets weird, a WC sooner than later is usually a good idea.

I’d be weary of dosing P or N directly long term though it’s a great way to fix an N/P imbalance such as when your algae or bacteria are limited by one or the other. I keep some of these chemicals available and use them quite rarely but they are good when needed. Long term hopefully you can find a good balance of import/export to get where you want to get with those parameters without dosing.

I would rather avoid rip clean since I don't have another tank where to relocate temporarily my stuff. Also fish and inverts look healthy, better not to play with fire.

I agree with you, if it were my tank I also wouldn’t do a rip clean just thought I’d mention the thought. If your inhabitants are healthy, short of the dino issue and wanting to add corals, it could be argued you don’t even have an issue.

Yes this is also what the guy at my LFS told me. I am just a bit ticked because everything comes with big costs with this hobby and if I can manage to solve the problem without buying a lot of unnecessary items I would rather try that way. Many people told me that skimmer is not necessary since I have so many macros, but I did not consider the problem with pH. My plan now would be to raise kH to the upper limit (11-12 dkH) and see how it goes with pH. If stays stable around 8 despite CO2 higher than usual I would be happy. If it does not work I am going to either install a sump or get a hob skimmer and co2 scrubber.

Well you don’t need a skimmer. It’s a choice, I’ve always run one but plenty of people don’t and have wonderful tanks. A skimmer is just one tool you can consider.

We know thriving macro algae can control nutrients and you wouldn’t be wrong at all for using that entirely.

For pH, many people run at 7.8 ish with no issue and I’m still not convinced 7.5 was an accurate measurement. But out of experience getting the pH up would benefit your tank. The skimmer/CO2 scrubber can be a valuable tool for this.

The thing is, a scrubber basically consumes CO2 from the feed air to the skimmer which assuming your ambient air is high CO2, then pulls CO2 from the water -> pH goes up. But another angle is that your macro while photosynthesizinshould suck CO2 out of the water do the same thing.

So if you made the choice to use macro algae as your primary nutrient export method I think we can still get your pH up without a skimmer. That’s to say if you add a skimmer I wouldn’t suggest you do it for pH alone. A good one certainly isn’t cheap. And keep in mind if the ambient CO2 is really high, if adding a skimmer but not CO2 scrubbing or running a line outside you might lower the temperature pH further.

I’d still go the high pH 2 part before the skimmer. Also if wanting the benefits of CO2 scrubbed air but don’t want a skimmer, we really could consider a CO2 scrubbed airline feeding an airstone after your refugium.

Actually my tank is skimmerless now as I’m upgrading and removed the old skimmer while the new skimmer hasn’t yet arrived. pH lower as expected, but still bottoms out at 8.1-8.2 and goes to 8.4 before lights out.

So in sum I think we can get you where you want to be with or without a skimmer.

KH 11-12 should be fine but go there slowly. I have heard people say corals are more likely to RTN at very high alk but no idea if it’s real. As you push alk up, you’ll see a pH increase if everything else is constant. Just take it slow and steady, and if you have issues stop increasing it further.

What's the difference with Na3CO3 only? I tested Ca and Mg and they are in the right range, giving that I have no corals yet. Maybe coralline could be using those in the long term.. I can see it growing quite fast on the back of the tank.

Ca and Mg wouldn’t be directly related to your alkalinity dosing but of course will be consumed with alkalinity so great that they’re where you want them. It’s a very good sign that you have coralline. In many ways it means you already have a good enough environment for many corals.

For alkalinity, about the differences, if we consider 3 options, the differences are in the second half of the formula (the “negative” side”), call them option:

1. NaHCO3 (sodium bicarbonate)
2. Na2CO3 (sodium carbonate)
3. NaOH (sodium hydroxide)

Long story short, in the end once everything is in equilibrium, there is no difference as all of these species exist anyway in equilibrium in the water. But upon adding them, at first you’ll see a pH effect with item 1 giving no big impact or even a slight decrease, while 2 would give a moderate pH increase, and 3 would give a significant pH increase. This also tells you the amount of caution and care you should use when adding them, in numerical order

Item 3 is a strong base, it’s what’s in Drano anyway. So handle with care, don’t get it on you and especially not in your eyes, and dose only tiny amounts frequently and into high flow. Use Randy’s recipes if going 2 part, to prevent long term ionimbalances over time.

If not using a quality dosing pump I’d avoid NaOH personally.

Yes good point. I have no dosing pumps yet (I actually don't even have a decent led for corals yet), but I can just manually dose every morning and evening dividing the solution 14 times.

Well, just get dosing pumps when it makes sense for you. Lights are probably the better investment. I actually manually dose everything I use besides 2 part manually as I enjoy it.

But if dosing manually I’d avoid option 3. And keep an eye out for pH effects right after adding them

Thanks so much for the advice. I am not too much concerned until my livestock is healthy and eating, but until I solve this ph and dino problems I don't want to add corals. Which is annoying but, well, better to wait than to waste money and corals.

My pleasure. I think you’re doing the right things. Your tank inhabitants are healthy, that says more than any test can and I wouldn’t base not adding corals just on a pH concern.

You’ve got a reef tank and you want to add corals. Livestock is healthy and algae including coralline is growing. It’s normal for you to want to add corals, and I’d say if it were my tank, even considering your situation, I’d add some bulletproof ones.

Personally I’d say don’t make yourself wait over test results. Leathers, green nepthea, mushrooms of the beautiful but affordable variety, green star polyps. Perhaps Xenia. Zoas. Really, these are essential impossible to kill and they don’t need that much light.

If the unlikely but still possible situation of them dying worries you, just plan a LFS or friend as a pre agreed backup to take them and babysit them for a while if you run into trouble.

If it were me at this stage, I’d add a a single nice looking leather or some GSP. Maybe a green nepthea. See how it goes. And even if you’re going mainly SPS later, these can still fit in beautifully

You might be surprised by your success.

Adam

 

[Adam1985]

Yeah I am at 33.5 ppm. I am aiming for 35 but as you said that does not explain such drop in kH..

KH can get to 8 or a bit below even if your water mixes to 11. Just need to understand what’s consuming it or how it’s being consumed.

Goes without saying, salinity measurements can be off. Very off. Usually not enough to cause huge issues as long as you’re consistent, but off nevertheless. If salinity ends up being in question we should address that. But sounds like you’ve got it covered and as said, consistency is key.

Also had reread one of Randy’s comments that algae is usually not going to consume enough CO2 to solve an ongoing pH issue due to high ambient CO2. I wanted to point out that I agree it’s usually not enough to fully eliminate the issue, but it should help somewhat if it’s growing well.

Good luck and we are happy to keep helping you until we’ve resolved the issue!

Adam

 

[KonradTO]

Thanks for the great help everyone is giving!
Yesterday I finally calibrated properly the pH meter in the lab, and tried with different buffers (they are new). It was only 0.11 off but well, now should do it's job better. So, there is no doubt at all that my pH is around 7.6-7.7 depending on the time of the day the sample is taken.
kH was slighlty below 8 and this is another certaint point. I am dosing slowly (over 1 week) sodium carbonate and expect a rise in 0.6-0.7 pH (following Randy's explanation an increase in 3dKh should increase pH by that much).
All the remaining "gap" in pH must be caused by CO2 then.
I left windows open very often in the last few days and I have not seen a particular increase in pH. Also I took the lid off.
How long it should take for the CO2 to "leave" the water surface? I am giving a lot of water turbolence for that.
What pH should I expect with a "normal" amount of CO2 in my system and alkalinity of about 8 dkH, for instance?
Where can I find the formula?

 

[arking_mark]

Thanks for the great help everyone is giving!
Yesterday I finally calibrated properly the pH meter in the lab, and tried with different buffers (they are new). It was only 0.11 off but well, now should do it's job better. So, there is no doubt at all that my pH is around 7.6-7.7 depending on the time of the day the sample is taken.
kH was slighlty below 8 and this is another certaint point. I am dosing slowly (over 1 week) sodium carbonate and expect a rise in 0.6-0.7 pH (following Randy's explanation an increase in 3dKh should increase pH by that much).
All the remaining "gap" in pH must be caused by CO2 then.
I left windows open very often in the last few days and I have not seen a particular increase in pH. Also I took the lid off.
How long it should take for the CO2 to "leave" the water surface? I am giving a lot of water turbolence for that.
What pH should I expect with a "normal" amount of CO2 in my system and alkalinity of about 8 dkH, for instance?
Where can I find the formula?

It's a more complicated model than a simple calculation, but there is a reef calculator for that...

Equilibrium pH Calculator

Aquarium calculator; Estimate the equilibrium pH of your aquarium assuming it is thoroughly aerated.

www.hamzasreef.com

I use the python PyCO2SYS library for my calculations...and I do get slightly different results.

 

[KonradTO]

Ok. This sounds about wrong, even if I know it's right..
Basically if I had dkH of 10 I would have an increase of only 0.1 in pH. My numbers make sense only if I have 2000 ppm of CO2 in my house, but I do feel completely fine at home and have one window open all night and the rest of them open from time to time.
Could it be that there is something else acidifing the water other than CO2? maybe something leaching?

 

[arking_mark]

If you take artificial saltwater and aerate it, it will quickly find CO2 equilibrium with the air.

However, this is not quite the right way to think about your tanks CO2 and therefore pH. You have to think of CO2 in terms of dynamic sources and sinks. As an example, assuming higher indoor CO2 air and a CO2 scrubbed skimmer with a mature tank with livestock, coral, and algae you would look at the following...

Tank CO2 = A (aeration with higher indoor CO2 through powerheads and return pumps) + B (CO2 from biological processes) + C (CO2 contributions from some types of dosing) - D (skimmer aeration with CO2 scrubbed air) - E (CO2 uptake through photosynthesis) - F (CO2 sinks from some types of dosing)

If we use outdoor air and natural seawater pH as a target ~ 8.2 NBS then

If A+B+C > D+E+F, then tank CO2 will be higher and pH < 8.2 NBS.

Generally speaking. B+C contribute little and if you have no contributions from D+E+F, your worst case scenario is tank in equilibrium with your higher CO2 air. Hence tanks can never be worse then 7.8 NBS unless your indoor air quality is at an unhealthy level for humans which is almost always NOT the case.

So when someone says their pH is below 7.8, its usually one of three things:

1. Poor tank aeration
2. Inaccurate pH measurement
3. Unhealthy indoor air quality

 

[arking_mark]

Ok. This sounds about wrong, even if I know it's right..
Basically if I had dkH of 10 I would have an increase of only 0.1 in pH. My numbers make sense only if I have 2000 ppm of CO2 in my house, but I do feel completely fine at home and have one window open all night and the rest of them open from time to time.
Could it be that there is something else acidifing the water other than CO2? maybe something leaching?

Yes. Increasing Alk will boost your baseline pH...and lets look at just equilibrium with well aerated sea water:

Alk dKH	CO2 = 400 ppm (~ outdoor air)	pH NBS
7	400	8.22
8	400	8.27
9	400	8.31
10	400	8.35
11	400	8.38

Alk dKh	CO2 = 800 ppm (~ typical indoor air at the higher end))	pH NBS
7	800	7.97
8	800	8.02
9	800	8.07
10	800	8.11
11	800	8.14

As you can see, your pH shouldn't measure below 8 NBS unless something is off. Salinity, temp, and a slew of other things can impact these numbers...and I can run the model, but those impacts aren't as significant.

 

[arking_mark]

Yes. Increasing Alk will boost your baseline pH...and lets look at just equilibrium with well aerated sea water:

Alk dKH	CO2 = 400 ppm (~ outdoor air)	pH NBS
7	400	8.22
8	400	8.27
9	400	8.31
10	400	8.35
11	400	8.38

Alk dKh	CO2 = 800 ppm (~ typical indoor air at the higher end))	pH NBS
7	800	7.97
8	800	8.02
9	800	8.07
10	800	8.11
11	800	8.14

As you can see, your pH shouldn't measure below 8 NBS unless something is off. Salinity, temp, and a slew of other things can impact these numbers...and I can run the model, but those impacts aren't as significant.

...and If you open windows in your house and air is flowing, your CO2 will very quickly (in minutes) get to outdoor levels.

 

[KonradTO]

...and If you open windows in your house and air is flowing, your CO2 will very quickly (in minutes) get to outdoor levels.

This is why I doubt the problem is with indoor CO2, but there are not other factors actually. If I tested pH with 3 different probes and all of them gave me results lower than 7.8, I can be quite sure pH is around that number, maybe 0.1 higher or lower but no far from that. I do not feel the house is more sealed than others, actually the contrary is true. The tank is in the kitchen, but there is not free fire or gas (we have electric stove). I open the windows frequently for few minutes and all night long in the bedroom. DkH is another thing I am quite sure about, as I tested it with my tests and with the lfs tests and both were giving similar values.

I cannot think of anything else to be honest. Could it because of exhausts of a chimney? the owners of the house live on the ground floor and have a fireplace, and the chimney pass along our flat, but gets cleaned frequently.

 

[KonradTO]

This is why I doubt the problem is with indoor CO2, but there are not other factors actually. If I tested pH with 3 different probes and all of them gave me results lower than 7.8, I can be quite sure pH is around that number, maybe 0.1 higher or lower but no far from that. I do not feel the house is more sealed than others, actually the contrary is true. The tank is in the kitchen, but there is not free fire or gas (we have electric stove). I open the windows frequently for few minutes and all night long in the bedroom. DkH is another thing I am quite sure about, as I tested it with my tests and with the lfs tests and both were giving similar values.

I cannot think of anything else to be honest. Could it because of exhausts of a chimney? the owners of the house live on the ground floor and have a fireplace, and the chimney pass along our flat, but gets cleaned frequently.

But if this was the reason I guess I would smell something..

 

[arking_mark]

But if this was the reason I guess I would smell something..

It could very well be that your tank pH is 7.5 NBS with a small tank and closed lid.

However, if you take tank water out and aerate it...numbers should align with model.

Also, your meter may be measuring pH Total vs NBS. There is about a .13 difference between the two.

So based on your last measurements of 7.6 to 7.7, if your meter is +/- .1 and it measures pH Total, then your NBS pH (witch most people use) might very well be 7.8 to 7.9 NBS and in the expected range.

I've personally spent a ton of time chasing pH and had fun doing it. However, I'm not sure there is a lot of benefit to a reef tank other than increased stability which is generally important.

If your tank is properly aerated, you don't really ever need to worry about pH...and many don't.

Here is my last week of pH, which ranges normally from 8.23 to 8.29 NBS (you can see the higher highs > 8.3 when windows are open) . Highs are during peak lighting when I have the most photosynthesis and lows are at night. My indoor CO2 levels are generally between 600-800ppm. Alk is usually ~7.7dKH but reading have been between 7.7 and 8.4 dKH lately (may need to recalibrate the meter). To get this level of control, I use Kalkwasser, a reverse lighting schedule refugium, and a valve controlled oversized CO2 scrubber that can raise or lower my CO2 levels.

As you can see, windows open and people in the house can have a substantial impact on the CO2 levels.

Having a tightly closed lid on your tank may be an issue...I use a mesh lid.

 

[KonradTO]

It could very well be that your tank pH is 7.5 NBS with a small tank and closed lid.

I cannot find an indication wheather the pH probe we have in the lab uses one scale or the other, I actually never heard of it. I mean total pH means you have to measure separately many things right? The one in the lab is a normal pH meter.
On the buffer side I ordered some new buffer to check if that's the problem.

Having a tightly closed lid on your tank may be an issue...I use a mesh lid.

I mean, I wouldn't say is tight. I don't know how much space is necessary to let enough fresh air in, but is not tight for sure. I have a portion of 60x3cm where is not covered and a 15x10 section where it's cut for the automatic feeder. also the filter section is not covered at all and there is a lot of water movement in there.

I did an aeration test with an airstone outside for 1h but pH increased only by 0.1 pH (from 7.65 to 7.73).
I would like to eliminate any doubt by taking some air from outside but I cannot drill an hole in the window or in the wall, my landlord would be quite p>***ed off.

 

[arking_mark]

I cannot find an indication wheather the pH probe we have in the lab uses one scale or the other, I actually never heard of it. I mean total pH means you have to measure separately many things right? The one in the lab is a normal pH meter.
On the buffer side I ordered some new buffer to check if that's the problem.

I mean, I wouldn't say is tight. I don't know how much space is necessary to let enough fresh air in, but is not tight for sure. I have a portion of 60x3cm where is not covered and a 15x10 section where it's cut for the automatic feeder. also the filter section is not covered at all and there is a lot of water movement in there.

I did an aeration test with an airstone outside for 1h but pH increased only by 0.1 pH (from 7.65 to 7.73).
I would like to eliminate any doubt by taking some air from outside but I cannot drill an hole in the window or in the wall, my landlord would be quite p>***ed off.

That aeration test is what makes me doubt the test...it's not a reasonable result unless there is something else going on.

 

[KonradTO]

As an example, assuming higher indoor CO2 air and a CO2 scrubbed skimmer with a mature tank with livestock, coral, and algae you would look at the following...

I considered also getting a CO2 scrubber but it seems that it's really expensive in terms of media. I would rather give up on sps

 

[arking_mark]

I considered also getting a CO2 scrubber but it seems that it's really expensive in terms of media. I would rather give up on sps

Many people are successful with SPS without boosting pH.

 

[KonradTO]

That aeration test is what makes me doubt the test...it's not a reasonable result unless there is something else going on.

Which test do you mean? the areation test?
The only thing left to do which I did not try yet is measuring saltwater. There dkH is supposed to be 11-12 and ph 8.3. if it's not then salt is the problem I guess

 

[arking_mark]

Many people are successful with SPS without boosting pH.

In fact, the only proven benefit is that some coral grow faster.

If we make a car analogy, higher pH is like having a faster car...does your tank speed matter that much? For coral farmers, that is a definate yes. For hobbiest, maybe not so much.

 

[arking_mark]

Which test do you mean? the areation test?
The only thing left to do which I did not try yet is measuring saltwater. There dkH is supposed to be 11-12 and ph 8.3. if it's not then salt is the problem I guess

Your outdoor aeration lest.

Also, that salt pH is still dependent on CO2 levels. So as it mixes and aerates, it will try to equilize with the CO2 in the air.

 

[KonradTO]

As far as I understood a pH of 7.6-7.7 is too low for organisms made of CaCo3.. But apparently there are some people out there with low pH and corals