A few months ago I had a distressing experience with pH fluctuations, and I thought I would relate it for those who might want to know. I tried some of the advice in this forum, and unfortunately some of it made things worse. I was also guilty of allowing a bit of panic override my better good judgement.
First of all, let me comment that the first thing many people ask is, "Are you sure the <name your equipment> is accurate. It is a very good question, and anyone who is experiencing sudden perplexing parameter shifts should do is re-calibrate their equipment to known standards. I also recommend using more than one testing method, as sometimes there can be unanticipated environmental effects that skew the readings. Using more than one method (e.g. indicator solutions plus electronic testing, indicator solutions using different base chemicals, etc.) will tend to eliminate systemic errors produced by otherwise superfluous influences.
Secondly, I personally suggest one test as many parameters as one can when one parameter is out of whack. It is not unusual that one water parameter will actively affect other factors, and it may well be the root cause of the issue may have to be addressed differently than directly trying to modify the initial indicator. Temperature, for example, can have both direct and indirect effects on many qualities of water, and getting the temperature back in line may well produce secondary effects that normalize various aspects of water chemistry as the biological processes reach a proper equilibrium.
I am still not certain what the actual cause of the issue was, but here is what I did and what consequently (I presume) happened:
I was having some problems with a rather massive algae bloom in my aquarium (100g). I had a small ball of chaeto that had become huge, and both the filamentous algae and cyanobacteria had virtually obscured everything in the tank that did not move. I removed most of the chaeto and purchased a yellow tang. I added some phos-sorb to one of the filters and did a moderately large water change (25%) followed by 5 gallon water changes every 3 days. I reduced the lighting period by 2 hours. At that time I did not yet have a phosphate test kit on hand, so I don't really kow how high the phospate may or may not have been. Nitrates were a bit high. I also did not have a water hardness kit at that time, but I knew the water was fairy hard. How hard, I later found out. The pH level was consistently above 8.2.
In just a couple of days, the algae started disappearing quite rapidly. I was quite pleased. Having made some changes, I was keeping a fairly close eye on the water chemistry with all the tests I had in hand, and everything was looking both great in magnitude and quite stable. Then one afternoon about 3 days after the last water change, I walking into the room and all my soft corals were wilted and limp. I immediately checked everything I could, and the only parameter out of whack was the pH, at 7.8 by the chemistry test. I did not have a pH meter. I had bought one, but it was defective, and the replacement had not arrived.
I immediately the recommended dose of pH 8.3, and the pH rose a bit, but then quickly dropped back to 7.8. This continued for several days, until the new pH meter arrived. Although it read the same as the chemical indicator, I was able to see changes more on a real-time basis, and of course more accurately. I kept adding more and more buffer, but no matter what, the pH would always rise for a few minutes and then plummet back to between 7.8 and 7.9. Obviously, something was buffering the water to around 7.8, but I had no idea what. All of the fish were feeling a bit poorly, not eating very well. The soft corals would recover a bit, but then droop again when the pH fell below 8.0.
One of the first things I read here was the suggestion it could be excessive atmospheric C02. I did not see how, since this is a fairly large house and only two of us live here with 2 cats and a Shi Tzu, but I ordered a CO2 scrubber,, anyway. What's more, it is an older house, so it is not sealed tight like some more modern houses. The room itself is fairly large (~ 400 sq ft), adn I am the only one who stayes in it for any length of time. I increased the aeration while waiting for the scrubber to arrive from Europe. There was no noticeable change.
Realizing the 8.3 buffer contained both basic and acidic components, I decided to switch from it to pure NaHCO3. When dosing either the 8.3 buffer or the baking soda, I mixed the powder with a liter of water from the tank before introducing it into the sump. I noticed a fairly significant amount of precipitates formed when mixing the solution. I took it to merely be an artifact of common ions in the aquarium water. I should have paid better attention.
The NaHCO3 did a better job of raising he pH above 8.0 for a few minutes, but then the pH would plummet below 7.9 again. Once more, I should have been paying better attention to what the water was telling me, and to the fact that even though I had instituted two more 25% water changes, the pH level remained intractably low.
The pH meter arrived.
While I was able to monitor the pH level more accurately and continuously than the indicator solution kit, but the effects in the tank remained the same. Then one time when I was dosing the tank with NaHCO3, I noticed some white precipitate forming on the glass of the aquarium. Again, I should have paid more attention. After another dose, the pH nose dived to 7.5, and adding NaCO3 had no effect. A large amount of white precipitate obscured most of front of the tank. I did a massive 50% water change, to no effect. The Colt corals died. The fish were all hiding, and I supposed at least some were dead, although I found no bodies.
I finally got it through my head the water was essentially too hard. I had never considered such a thing to be possible, but it seems to have been the case, and the precipitate was probably mostly CaCO3, with the water being supersaturated with NaHCO3 and some acid - probably sodium tetraborate - buffering the water to 7.5.
I started carefully dosing the tank with 15ml of a 10% solution of NaOH. The pH would rise between .03 and .04 and then fall back about .02, slowly inching upward. I continued dosing every couple of hours. When the pH rose above 8.1 and stayed there, the fish all started coming out and swimming around. Soon they began to eat voraciously. I did not lose a single fish, thank goodness. The crustaceans and molluscs all seem to have come through just fine, although there are too many tiny snails and crabs in the tank to be sure I didn't lose a handful. I dropped the dosage to 10ml and then to 5ml when the pH rose above 8.2 and stayed there. I stopped altogether when the tank stabilized right around 8.25, dropping to about 8.22 at night and peaking at about 8.29 during the day.
Along the way the CO2 scrubber came in, and while it did raise the pH by a few hundredths, the effect was not huge, so I think I am correct in discounting atmospheric CO2 as the principle contributor. I scaled back the water changes to 5 gallons a week. I was buying my water ready-mixed from the LFS. When I obtained a water hardness test, I checked on the aquarium water, and it was completely hard, never changing color at all. I confirmed by mixing the aquarium water 50% with distilled water. The hardness of the resulting solution measured 7. I checked the water from the LFS, and it measures 11. The hardness of untreated water from one of my outside hydrants also measures 11. I have a whole-house water softener, however, and the output from my sink faucet is under 1. I am now using water from my faucet to top off the sump.
Interestingly enough, while the pH remained very stable around 8.25 for several weeks, one night it began rising quite inexplicably. Eventually it topped off at 8.45, which is too high for my comfort, but the only inhabitant that seemed to mind much was the Sea Apple and the one LPS I have in the tank. Having had one bad experience, I was shy of trying to mess with moree chemicals in the tank, but I did not think it would be healthy for the tank to remain that high for long. I removed the CO2 scrubber and added 5ml of white vinegar. This helped, but once again it was not stable. The pH would always rise after a while. I stopped dosing with vinegar, and instead made up some carbonated water. This I dosed at 40ml as long as the pH remained above 8.25. Eventually it stabilized, but every now and then it still goes above 8.3, at which point I remove the CO2 scrubber and if the pH does not fall below 8.3 after a few hours, I dose with 20ml of carbonated water.
First of all, let me comment that the first thing many people ask is, "Are you sure the <name your equipment> is accurate. It is a very good question, and anyone who is experiencing sudden perplexing parameter shifts should do is re-calibrate their equipment to known standards. I also recommend using more than one testing method, as sometimes there can be unanticipated environmental effects that skew the readings. Using more than one method (e.g. indicator solutions plus electronic testing, indicator solutions using different base chemicals, etc.) will tend to eliminate systemic errors produced by otherwise superfluous influences.
Secondly, I personally suggest one test as many parameters as one can when one parameter is out of whack. It is not unusual that one water parameter will actively affect other factors, and it may well be the root cause of the issue may have to be addressed differently than directly trying to modify the initial indicator. Temperature, for example, can have both direct and indirect effects on many qualities of water, and getting the temperature back in line may well produce secondary effects that normalize various aspects of water chemistry as the biological processes reach a proper equilibrium.
I am still not certain what the actual cause of the issue was, but here is what I did and what consequently (I presume) happened:
I was having some problems with a rather massive algae bloom in my aquarium (100g). I had a small ball of chaeto that had become huge, and both the filamentous algae and cyanobacteria had virtually obscured everything in the tank that did not move. I removed most of the chaeto and purchased a yellow tang. I added some phos-sorb to one of the filters and did a moderately large water change (25%) followed by 5 gallon water changes every 3 days. I reduced the lighting period by 2 hours. At that time I did not yet have a phosphate test kit on hand, so I don't really kow how high the phospate may or may not have been. Nitrates were a bit high. I also did not have a water hardness kit at that time, but I knew the water was fairy hard. How hard, I later found out. The pH level was consistently above 8.2.
In just a couple of days, the algae started disappearing quite rapidly. I was quite pleased. Having made some changes, I was keeping a fairly close eye on the water chemistry with all the tests I had in hand, and everything was looking both great in magnitude and quite stable. Then one afternoon about 3 days after the last water change, I walking into the room and all my soft corals were wilted and limp. I immediately checked everything I could, and the only parameter out of whack was the pH, at 7.8 by the chemistry test. I did not have a pH meter. I had bought one, but it was defective, and the replacement had not arrived.
I immediately the recommended dose of pH 8.3, and the pH rose a bit, but then quickly dropped back to 7.8. This continued for several days, until the new pH meter arrived. Although it read the same as the chemical indicator, I was able to see changes more on a real-time basis, and of course more accurately. I kept adding more and more buffer, but no matter what, the pH would always rise for a few minutes and then plummet back to between 7.8 and 7.9. Obviously, something was buffering the water to around 7.8, but I had no idea what. All of the fish were feeling a bit poorly, not eating very well. The soft corals would recover a bit, but then droop again when the pH fell below 8.0.
One of the first things I read here was the suggestion it could be excessive atmospheric C02. I did not see how, since this is a fairly large house and only two of us live here with 2 cats and a Shi Tzu, but I ordered a CO2 scrubber,, anyway. What's more, it is an older house, so it is not sealed tight like some more modern houses. The room itself is fairly large (~ 400 sq ft), adn I am the only one who stayes in it for any length of time. I increased the aeration while waiting for the scrubber to arrive from Europe. There was no noticeable change.
Realizing the 8.3 buffer contained both basic and acidic components, I decided to switch from it to pure NaHCO3. When dosing either the 8.3 buffer or the baking soda, I mixed the powder with a liter of water from the tank before introducing it into the sump. I noticed a fairly significant amount of precipitates formed when mixing the solution. I took it to merely be an artifact of common ions in the aquarium water. I should have paid better attention.
The NaHCO3 did a better job of raising he pH above 8.0 for a few minutes, but then the pH would plummet below 7.9 again. Once more, I should have been paying better attention to what the water was telling me, and to the fact that even though I had instituted two more 25% water changes, the pH level remained intractably low.
The pH meter arrived.
While I was able to monitor the pH level more accurately and continuously than the indicator solution kit, but the effects in the tank remained the same. Then one time when I was dosing the tank with NaHCO3, I noticed some white precipitate forming on the glass of the aquarium. Again, I should have paid more attention. After another dose, the pH nose dived to 7.5, and adding NaCO3 had no effect. A large amount of white precipitate obscured most of front of the tank. I did a massive 50% water change, to no effect. The Colt corals died. The fish were all hiding, and I supposed at least some were dead, although I found no bodies.
I finally got it through my head the water was essentially too hard. I had never considered such a thing to be possible, but it seems to have been the case, and the precipitate was probably mostly CaCO3, with the water being supersaturated with NaHCO3 and some acid - probably sodium tetraborate - buffering the water to 7.5.
I started carefully dosing the tank with 15ml of a 10% solution of NaOH. The pH would rise between .03 and .04 and then fall back about .02, slowly inching upward. I continued dosing every couple of hours. When the pH rose above 8.1 and stayed there, the fish all started coming out and swimming around. Soon they began to eat voraciously. I did not lose a single fish, thank goodness. The crustaceans and molluscs all seem to have come through just fine, although there are too many tiny snails and crabs in the tank to be sure I didn't lose a handful. I dropped the dosage to 10ml and then to 5ml when the pH rose above 8.2 and stayed there. I stopped altogether when the tank stabilized right around 8.25, dropping to about 8.22 at night and peaking at about 8.29 during the day.
Along the way the CO2 scrubber came in, and while it did raise the pH by a few hundredths, the effect was not huge, so I think I am correct in discounting atmospheric CO2 as the principle contributor. I scaled back the water changes to 5 gallons a week. I was buying my water ready-mixed from the LFS. When I obtained a water hardness test, I checked on the aquarium water, and it was completely hard, never changing color at all. I confirmed by mixing the aquarium water 50% with distilled water. The hardness of the resulting solution measured 7. I checked the water from the LFS, and it measures 11. The hardness of untreated water from one of my outside hydrants also measures 11. I have a whole-house water softener, however, and the output from my sink faucet is under 1. I am now using water from my faucet to top off the sump.
Interestingly enough, while the pH remained very stable around 8.25 for several weeks, one night it began rising quite inexplicably. Eventually it topped off at 8.45, which is too high for my comfort, but the only inhabitant that seemed to mind much was the Sea Apple and the one LPS I have in the tank. Having had one bad experience, I was shy of trying to mess with moree chemicals in the tank, but I did not think it would be healthy for the tank to remain that high for long. I removed the CO2 scrubber and added 5ml of white vinegar. This helped, but once again it was not stable. The pH would always rise after a while. I stopped dosing with vinegar, and instead made up some carbonated water. This I dosed at 40ml as long as the pH remained above 8.25. Eventually it stabilized, but every now and then it still goes above 8.3, at which point I remove the CO2 scrubber and if the pH does not fall below 8.3 after a few hours, I dose with 20ml of carbonated water.
