All sorts of problems

[stazitto25]

Hello All,

As the title states, I am having all sorts of chemistry problems with my reef tank. I am totally confused and have read so many articles that I don't even know which way is up anymore. What I would like to do is have a nice clean sand bed, lower my PH and get my alk higher. I am thinking that the three are related, I just don't know where to start with it. Here are my problems:

-My PH swings from 8.35 - 8.7. I use a neptune lab grade PH probe.
-No matter how much alk I dose it does not go over 140 ppm. I use a Hanna checker.
-My sand bed is clumpy, but not rock solid, seems like algae. It is not really visible, it is when I clean it that I notice the whole top layer is clumped together.

Ph = 8.35 - 8.7
Alk = 140ppm
Calcium = 420ppm
Mag = 1240 - 1280
Phosphates = 0
Nitrates = 0
GFO
Carbon
Dose 1 part - that is only Alk as my water changes keep up with Calcium demands.

Please Help!

 

[Ponyboy]

How long has tank been running

 

[Ponyboy]

Do you check your numbers before it goes in tank to give you a comparison

 

[stazitto25]

Tank has been running for a year...Well I did move in September so I guess it would be for 6 months. I did get all new sand when I moved, which didn't really look right since the first week I had it. It was never clear like my original sand.

 

[Boomer]

You are fueling your own problem by continuing to add Alk buffers. This raise the pH and Alk, which cause the precip of calcium carbonate, which can lead to clumping of the sand bed. You NEVER add a Alk buffer for low pH. 99 % of all pH issues are from excessive high room air CO2. You can not stop the pH from dropping when dealing with CO2. You need to solve the CO2 issue, by removing trapped room air CO2. If that is an issue then drip Kalk. Kalk "eats" CO2 and raise the pH back up. When you lose Alk to precip it will take 20 ppm calcium for each 50 ppm Alk with it. You will never notice this drop in calcium usually.

Your tank is now in a ionic imbalance mess and needs a 50% water change to get things back to normal. Once things are more the way they should be, raise the Alk to where you want it. If you have low pH issues DO NOT ADD MORE ALK BUFFER. Remove the CO2.

Also clean the oH probe. As algae growing on the probe will raise the pH at the probe. That algae removes lots of CO2, raising the pH and giving you false tank pH readings.


As far as your Hanna Checker, check it with a test kit so you know it is right.

 

[Paul B]

Or do as I do, change the water and throw out your test kits, saltwater is very stable if you don't mess with it.
Hello Boomer, Nice to see you. It'sa been a long time shince I heard from you. Hope everything is great.
Paul

 

[Dan_P]

Hello All,

As the title states, I am having all sorts of chemistry problems with my reef tank. I am totally confused and have read so many articles that I don't even know which way is up anymore. What I would like to do is have a nice clean sand bed, lower my PH and get my alk higher. I am thinking that the three are related, I just don't know where to start with it. Here are my problems:

-My PH swings from 8.35 - 8.7. I use a neptune lab grade PH probe.
-No matter how much alk I dose it does not go over 140 ppm. I use a Hanna checker.
-My sand bed is clumpy, but not rock solid, seems like algae. It is not really visible, it is when I clean it that I notice the whole top layer is clumped together.

Ph = 8.35 - 8.7
Alk = 140ppm
Calcium = 420ppm
Mag = 1240 - 1280
Phosphates = 0
Nitrates = 0
GFO
Carbon
Dose 1 part - that is only Alk as my water changes keep up with Calcium demands.

Please Help!

If I have this correct, 140 ppm alkalinity corresponds to 2.8 meq/l (seawater is around 2.5 meq/l I believe) and if your water is in equilibrium with 350 ppm CO2 (outside air), pH should be in the 8.3-8.4 range. The other parameters seem OK as well.

A higher than theoretical pH means your tank is CO2 starved and this can happen during the day when the lights are on and CO2 is being consumed faster than is absorbed from the air.

A lower than theoretical pH indicates a higher level of CO2 than you expect with a tank in equilibrium with 350 ppm atmospheric CO2. This can happen when the lights are off. Also, homes typically have higher than 350 ppm levels of CO2 and would tend to cause aquarium water to be more acidic. Inefficient mass transfer between the air and aquarium water is another reason for excess CO2 in the aquarium.

Finally, seawater tends to run supersaturated in CaCO3, which is good for coral but also means it is on the verge of precipitating out when the pH/alkalinity rise or even if the right surfaces are present. So, high pH and your particular brand of substrate might be driving substrate clumping, although high pH is probably enough of a reason.

Question: What time of day does the pH hit 8.7?

 

[stazitto25]

@Boomer - Thanks for replying. Thank you for the advice. I will consider doing a 50% water change this weekend. I just have a few questions.
When you say "Alk buffer" are you referring to my two part dosing? I am currently adding a solution of Sodium Carbonate (Soda Ash) to help raise my alkalinity. I recently found out this slightly raises pH, so I will be switching to Sodium Bicarbonate.
Also, you said you never add a Alk buffer for low pH. Did you mean to lower pH? Right now my issue is that my pH is way too high (~8.7) during the day. I really want to try to find a way to lower it and hopefully stop my pH from swinging so greatly. Also, I would think that dosing Kalk would raise my pH even higher. I thought part of my problem was that my tank has a high concentration of oxygen, and not enough CO2.
I double check my test kits and everything is similar. Like you said, I think I have an imbalance, just want to make sure I am understanding this correctly before I act on it.

 

[stazitto25]

@Dan P - Thanks for your reply. I am thinking along the same lines as you are. According to my apex, my pH spikes at 8.7 around 5:20pm, which is 20 minutes after my daylights turn off. Normally no one is home at this time. I also notice that at whatever time I come home is when my pH begins to really drop.

 

[Boomer]

Dan P

350 ppm CO2 (outside air), pH should be in the 8.3-8.4 range

Outside air is 390 ppm, out in the rural areas. In town it can be higher. We just go by the norm if 390 ppm. And that gives 8.3 pH, not much difference.

A higher than theoretical pH means your tank is CO2 starved and this can happen during the day when the lights are on and CO2 is being consumed faster than is absorbed from the air.

Never seen this in 30 years. You may on a rare occasion see this in what we call Planted Marine Aquarium, where there is so much plant life it pulls all the CO2 out, which starts converting bicarbonate to carbonate. The answer is always using excessive buffer or overdosing with Kalk or Algae on the probe.




Staz

First thing you need to do is clean that probe before you do ANYTHING. More than likely you may getting those levels, as I said, from algae on the probe. Then recal it.

When you say "Alk buffer" are you referring to my two part dosing? I am currently adding a solution of Sodium Carbonate (Soda Ash) to help raise my alkalinity. I recently found out this slightly raises pH, so I will be switching to Sodium Bicarbonate.

Any buffer, that includes 2 part. Sodium carbonate is the worst at times due to its spiking pH effect. pH of BS ~ 8.3 and Soda Ash is ~ 11.5 pH.

Also, you said you never add a Alk buffer for low pH. Did you mean to lower pH?

No, you never add a buffer for raising the pH when you have low pH issues. Low pH issues are from CO2.

Also, I would think that dosing Kalk would raise my pH even higher. I thought part of my problem was that my tank has a high concentration of oxygen, and not enough CO2.

I said if one has low pH issues to use Kalk to remove the CO2. Go back and read the post again



Oxygen has nothing to do with CO2 or pH. And most tanks are really lower than the ocean in O2. The other issue many miss is a higher Alk will have more CO2 than a lower Alk at the same pH. Matter of fact, a pH of say 8.1, can have less CO2 than a tank with a pH of 8.2.

pH 8.1, Alk 100 ppm = 0.58 ppm CO2

pH 8.2, Alk 200 ppm = 0.88 ppm CO2


Again do nothing till you clean and recall that pH probe. You need to know if that pH is real, not a Algae on probe giving false readings.

 

[Boomer]

Hi Paul

Go to see you still around and into it Hope all is well.

 

[Paul B]

All is well, I never left it.

 

[Boomer]

Staz

By the way get or use something else to verify that pH. Got another guy with a Apex showing 8.5 pH.

 

[stazitto25]

Boomer

I am going to clean my probe tomorrow. I appreciate your help and will let you know if anything changes. I would use my api pH test, but I can never tell if it is accurate or not.

Thanks Again

 

[stazitto25]

Good News,

Made a rookie mistake and calibrated my pH probe incorrectly the first time. When I did it this time my pH is much lower. For the past two days my pH has been staying between 7.75 - 8.16. Although this is on the low side, I would much rather it be here than at 8.7! I did match this with another test kit to verify.

I am going to try to increase my two part slightly again and see if I can get my Alk a little higher.

 

[Dan_P]

Good to hear all is well!

Just to remind you about Boomer's advice, you cannot effectively raise the pH by increasing the alklinity. The strategy is to remove CO2. This is just how buffers work.

I am stuck in a similar situation, with my tank water stuck at 7.5. I am not losing sleep over it yet because the tank is cycling. Eventually, I am going to have to get fresh air into the basement to lower the CO2 levels to get the water closer to 8.

Duke had an intereting thread on this very same problem several weeks back. I meant to ask him how he finally resolved it.

 

[Sharkbait420]

Or do as I do, change the water and throw out your test kits, saltwater is very stable if you don't mess with it.
Hello Boomer, Nice to see you. It'sa been a long time shince I heard from you. Hope everything is great.
Paul

This man knows what he is talking about. Stop dosing.

 

[Boomer]

Dan

There are a number of ways that will make a big difference on removing excessive CO2.

1. A line to the skimmer air from outside air.

2. A Granular Kalk CO2 Scrubber. A DI type or PVC pipe containing the granular Kalk. The air is run through the container and the CO2 and moisture reacts with the Kalk converting the Kalk from Calcium hydroxide to Calcium Carbonate.

3. A Sodium carbonate or Sodium hydroxide liquid CO2 Scrubber. A 5 gal bucket with the solution. Your air tube goes to the bottom. The out tube is under the lid. The air bubbles rise through through the solution removing the CO2 as it rises to the surface under the lid, where the lid tube pushes it out under accumulated pressure.

4. 2 PVC or plastic tubes, where one pulls in outside air and blows it across say the right end of the tank and another tube on the left end to the outside that sucks the CO2 to the outside. You need two fans, one a pulling fan, pulling in outside air and one a pushing fan, pushing the air outside. Best on tanks with cover lids. Open tanks won't do much.

Theses methods are all proven and can raise the pH from 0.2- 0.4 pH units in low pH tanks. Remember these are all from high room air CO2. High tank generated CO2, usually a rare issue but does happen in dirty/ over fed tanks, is a different issue.

To say it again, people, as Dan put it "you can not effectively raise the pH by increasing the alkalinity" When you try this the pH does rise, as does the Alk. The CO2 re- enters the tank, the pH drops. You do it again and again and what happens ? The same. The pH goes back to the same and now your Alk is through the roof. Adding buffers does nothing for low pH issues from CO2. Meaning, increasing or decreasing the CO2 does not change the Alk. You can prove this with a glass of water and a pH meter or kit when you blow air into the glass with a straw. The pH will drop the Alk will not change. And adding Kalk to the water is a little different as it reacts with the CO2 giving bicarbonate, a buffer.

Ca(OH)2 + 2CO2 -----> + 2HCO3- + Ca--

 

[stazitto25]

Great advice guys thank you everyone, question though: If I stop dosing my tank with Alk, is there a different way to supplement it? I need someway to keep up with the demands of my corals as I have a lot of SPS.

 

[vio]

Boomer, i found this on the net,
"...or do nothing.

There is nothing wrong with your tank. pH is controlled by the concentration of CO2 in the water, and as there are photoautotrophs* (organisms that use photosynthesis to make carbohydrates and simple amino acids out of CARBON DIOXIDE) in the tank, they will CONSUME CO2 during the time that the light is on, reducing the amount of CO2 and causing the pH to rise to a normal daily high of anywhere from 8.3 to 8.5. This changes when the lights go out, as the photoautotrophs lose the energy(light) that drives photosynthesis, AND THEY BECOME NET CONSUMERS OF THE CARBOHYDRATES THEY MADE DURING THE DAY (CHO's). This means that they "burn" the CHOs for chemical energy and break them down back into CO2, which they dispose of into the water column as a waste product. Increasing CO2 causes DECREASING pH, as low as 7.8 normally depending on how many and how dense the populations of the photoautotrophs are in the water. It is totally normal to see a daily swing in pH on a diurnal scale. As the normal pH of seawater is 8.2-ish depending on what time of day (and the consequential concentration of dissolved CO2 is in the tank water), expect to see a swing from a normal nadir of 7.9 to a peak of 8.4 without consequence to your tank inhabitants. The reason that even with normal levels of alkalinity that this swing occurs is due to the RATE of the changes in the concentration of CO2. The rate of change in CO2 concentration due to photosynthesis is at a greater rate and scale than buffer can compete with, even though it does prevent large swings to extremes based on how much CO2 is produced or removed by the organisms in the water column beyond the extremes of these ranges as new products of the carbonate/bicarbonate buffer system begin to appear with shifts in pH (other factors begin to come into play at these extremes based on degassing of CO2 and solubilization of solid CaCO3 substrates at the extremes). Remember also that we have much more dense populations of these organisms in small closed systems than exist in the scale of oceanic population densities.

Higher concentration of CO2 CAN have unusually effects on buffer capacity and visa versa, best summed up in the following chart:

Ratio pCO2 For ASW compared to NSW
VALUE IN CHART IS COMPARED TO A VALUE OF 1 FOR nsw AT SEALEVEL, OR x:1

Total Alkalinity (AT)
(mEq/l) . . . 2.0 .. 2.5 .. 2.6 .. 3.0 .. 3.5 .. 4.0 .. 4.5 .. 5.0 ... 5.5 ... 6.0
(dKH) . . . . 5.6 .. 7.0 .. 7.3 .. 8.4 .. 9.8 . 11.2 . 12.4 . 14.0 . 15.4 . 16.8
pH __________________________________________________ _________
7.7---------3.0 .. 3.7 .. 3.9 .. 4.5 .. 5.3 .. 6.0 .. 6.8 ... 7.5 ... 8.3 ... 9.1
7.8---------2.3 .. 2.9 .. 3.0 .. 3.5 .. 4.1 .. 4.7 .. 5.3 ... 5.8 ... 6.4 ... 7.O
7.9---------1.8 .. 2.2 .. 2.3 .. 2.7 .. 3.1 .. 3.6 .. 4.0 ... 4.5 ... 5.0 ... 5.4
8.0---------1.3 .. 1.7 .. 1.8 .. 2.0 .. 2.4 .. 2.7 .. 3.1 ... 3.4 ... 3.8 ... 4.1
8.1---------1.0 .. 1.3 .. 1.3 .. 1.6 .. 1.8 .. 2.1 .. 2.3 ... 2.6 ... 2.9 ... 3.1
8.2---------0.8 .. 1.0 .. 1.0 .. 1.2 .. 1.4 .. 1.7 .. 1.8 ... 2.0 ... 2.2 ... 2.4
8.3---------0.6 .. 0.7 .. 0.7 .. 0.7 .. 1.0 .. 1.2 .. 1.3 ... 1.5 ... 1.6 ... 1.8
8.4---------0.4 .. 0.5 .. 0.5 .. O.6 .. 0.7 .. 0.9 .. 1.0 ... 1.1 ... 1.2 ... 1.3
8.5---------0.3 .. O.4 .. 0.4 .. 0.5 .. 0.5 .. 0.6 .. 0.7 ... 0.8 ... 0.9 ... 0.9
8.6---------0.2 .. 0.3 .. 0.3 .. 0.3 .. 0.4 .. 0.4 .. 0.5 ... 0.6 ... 0.6 ... 0.7
__________________________________________________ ____________

Once the total alkalinity and pH are known, the ratio between the partial pressure of CO2 due to the atmosphere on seawater and the actual pC02 of the system being evaluated can be determined utilizing the above chart. With the value from the chart known, you can decide whether you need to start ventilating the tank with outside air to your skimmer (or fans to the surface or remove glass tops) to degas the CO2 content or if you need to increase your alkalinity.

For example, if your alk in the tank is 10 dKH (9.8 is close on the chart) and you measure a pH in the water of 8.3, then you will read a value of ?1.0? on the chart, telling you that your CO2 ratio is 1:1 with NSW during a normal day in the ocean. If you were to read a pH value of 7.9, you would know that your CO2 concentration is about 3 times what it would be in a daytime ocean reading, so it would be time to provide better gas exchange in your tank. If it were 7.7, then your tank would have 5.3 times the CO2 of NSW: in that tank, you would be having problems, either a tight lid or glass lids or a misbehaving CO2 solenoid or controller for a calcium reactor." C/P
I would like to make an experiment to set up a new fish tank, with less fish and corals. To see if theres any difference in the PH in the same room. Do you think there will be a difference ?!. Thank You.