Help with KH 19!!!!

[Icegirl]

Hi,
I have recently finished cycling a 50 gallon aquarium in my classroom. Currently there are 2 clownfish, 6 hermit crabs, 3 snails, and a serpent starfish. The school ran out of money before they could buy my light, and the assistant principal just ordered a 48 watt light yesterday, so I have nothing that photosynthesizes.

I have been having problems with my pH and KH due to the nature of this location.

Throughout my cycle I have been noticing that my pH was consistently low, with the windows open (the DOE turns on way too much heat), my pH was usually between 7.9 and 8.1. After a 3 day weekend where I wasn't allowed in the building the maintenance staff closed the windows and when I returned the pH was 7. I purchased a carbon dioxide monitor for my classroom and noticed that when the classroom is empty and all the windows are open, it is usually in the 1700 ppm range, and when I have students, it rises quickly to 3000 ppm or higher. (every other classroom is worse because somehow the teachers there don't mind the oppressive heat and keep the windows closed, no wonder all the students are always falling asleep in their desks or complaining of headaches!) I put notes on all the windows not to close them unless the carbon dioxide levels are in triple digits. Maintenance always closes the windows at night because otherwise the rats crawl in and wreak havoc in the classrooms.

Before adding animals I put a lump of crushed corals to try to prevent the pH from dropping. i wasn't testing kh yet. This was about a week ago and since then I have added the animals. Today I went into the classroom and tested the kh for the first time. It was 19, despite the pH never once having risen above 8.0, ever. Is this dangerous for the animals I currently have, and what can I do about this problem? I don't want to dilute it with RODI water because it's hard to access, only one person is strong enough to get the jugs back and forth from the LFS to the car to the building and that person is very much not me. In addition, the salinity is only 31 ppm currently on both my Hanna and my hydrometer, and I want to raise this up before getting corals.

Is there any possible source of this problem that I'm missing, and what can I do about it?

 

[Garf]

Did you use tap water to mix up the water? Or perhaps been adding a pH buffer?

 

[Randy Holmes-Farley]

I don’t think your CO2 values are correct. An empty room with windows open will have 400-500 ppm CO2.

Did you add anything to the tank to boost pH (don’t).

How are you measuring alkalinity?

Did you use tap water? It can have more alkalinity than seawater.

 

[Icegirl]

Did you use tap water to mix up the water? Or perhaps been adding a pH buffer?

I haven't used tap water. I've been using RODI water from the LFS and Imagitarium ocean water. The only buffer I used was 2 pounds of crushed coral in a little net bag to try to keep the pH from going back down to 7, which worked.

 

[Icegirl]

I don’t think your CO2 values are correct. An empty room with windows open will have 400-500 ppm CO2.

Did you add anything to the tank to boost pH (don’t).

How are you measuring alkalinity?

Did you use tap water? It can have more alkalinity than seawater.

I get RODI from the LFS and Imagitarium ocean water in a box.

The only buffer I used was 2 pounds of crushed coral in a net to prevent the pH from dropping back down to 7, which seemed to work. It hasn't gone below 8. It also hasn't gone above 8. It just stays at 8.

I tested the alkalinity using an API test kit.

I am pretty confident in the co2 monitor. My non scientific tests on it: I walked into the room in the morning and opened the window, then checked the monitor and it was at 1700. I was only there for a few hours, it did not go down much. During the week, if I'm alone in the classroom for several hours with the window open it goes down to 700-800ppm. It's never been below 700 while I was there. I once brought the monitor home, and it was between 500 and 600. On the balcony downstairs, it was 450. The monitor seems to be pretty accurate. FYI, the classroom STINKS of sweat. In fact, the whole school stinks of sweat.

How long do I have to bring the KH down before my animals start to get sick?

 

[Randy Holmes-Farley]

I haven't used tap water. I've been using RODI water from the LFS and Imagitarium ocean water. The only buffer I used was 2 pounds of crushed coral in a little net bag to try to keep the pH from going back down to 7, which worked.

To be fair, I don’t believe the pH actually got that low, but if somehow it did due to CO2 being dangerously high to the students in the room (above 4,000 ppm) , then the crushed coral will begin to dissolve and that raises alkalinity.

 

[Icegirl]

To be fair, I don’t believe the pH actually got that low, but if somehow it did due to CO2 being dangerously high to the students in the room (above 4,000 ppm) , then the crushed coral will begin to dissolve and that raises alkalinity.

The volume of the crushed coral is about a third less in the net than I originally put.

Before I added it, the pH hovered consistently between 7.7 and 7.9. It reached 8 like once or twice. After the crushed coral, it's been a consistent 8 and once 8.2

Should I take the crushed coral out? Is there another safe and natural way to increase pH without increasing alkalinity?

 

[Randy Holmes-Farley]

The volume of the crushed coral is about a third less in the net than I originally put. Should I take the crushed coral out?

Yes, take it out. The high alk is part of why the pH is now higher.

There are ways to reduce the alk, but I’d just watch it for a bit. The ways to reduce it when fish are present would involve adding an acid very slowly (lowers pH again) or doing water changes with a low alk mix (maybe made esoecially low).

 

[Garf]

I get RODI from the LFS and Imagitarium ocean water in a box.

The only buffer I used was 2 pounds of crushed coral in a net to prevent the pH from dropping back down to 7, which seemed to work. It hasn't gone below 8. It also hasn't gone above 8. It just stays at 8.

I tested the alkalinity using an API test kit.

I am pretty confident in the co2 monitor. My non scientific tests on it: I walked into the room in the morning and opened the window, then checked the monitor and it was at 1700. I was only there for a few hours, it did not go down much. During the week, if I'm alone in the classroom for several hours with the window open it goes down to 700-800ppm. It's never been below 700 while I was there. I once brought the monitor home, and it was between 500 and 600. On the balcony downstairs, it was 450. The monitor seems to be pretty accurate. FYI, the classroom STINKS of sweat. In fact, the whole school stinks of sweat.

How long do I have to bring the KH down before my animals start to get sick?

Are you replacing evaporation with tapwater or saltwater? Are you able to check salinity?

 

[Icegirl]

Are you replacing evaporation with tapwater or saltwater? Are you able to check salinity?

I have been replacing evaporation with the RODI from the LFS. I've been using a Hana to check salinity and today a hydrometer to check SG, which was at 1.024. It was at 30 ppt two days ago. We want to add corals soon, so we have been topping off with saltwater to slowly increase the salinity for 2 days. Now it's at 31 ppt. No tap water, unless the LFS lied to my assistant principal.

The hydrometer is the big glass one sold at Bulk Reef Supply

 

[Garf]

No tap water, unless the LFS lied to my assistant principal.

It'll be useful if you could check the alkalinity of the RODI, just to rule that out.

Edit - you could check new saltwater while you are at it.

 

[Icegirl]

It'll be useful if you could check the alkalinity of the RODI, just to rule that out.

i will do that

Is this a good plan: water changes to slowly get KH to normalish 10, then use baking soda to get the ph to 8.2 or 8.3. If so how much baking soda? And won't that be a temporary solution? Are my animals in danger right now? They seem ok but we just got them on tuesday. If it is the stale air (I think it is because that weekend that ph went down to 7, once I opened the windows the 3rd period class checked the parameters and it went up to 7.4, then by the last period it was up to 7.8...we test 4 times a day...each class has to test for learning purposes and I do a morning before class and an afternoon after class to make sure they get close to my numbers) how do I help the tank get air. We have 2 wavemakers, one 50 gallon hanging on back filter and two 30 gallon filter-skimmer all in one combo units

 

[Randy Holmes-Farley]

No, baking soda boosts alk and lowers pH.

I suggest doing nothing until things settle down. Water changes are ok, but don’t expect much progress lowering alk that way unless you lower the alk in the new salt water, or do very large ones.

 

[Garf]

use baking soda to get the ph to 8.2 or 8.3

Nah.

 

[Randy Holmes-Farley]

FWIW, stale air without people does not lower pH

 

[Randy Holmes-Farley]

If you really want to freak out students with the magic of pH chemistry, you can

1. Explain how adding totally pure fresh water at pH 7 to seawater at pH 8.1 raises the pH of the final mix above 8.1

Or

2. How adding a sodium bicarbonate solution at pH 8.5 to seawater at pH 8.1 results in a lower pH than 8.1 after mixing.

 

[Garf]

i will do that

Is this a good plan: water changes to slowly get KH to normalish 10, then use baking soda to get the ph to 8.2 or 8.3. If so how much baking soda? And won't that be a temporary solution? Are my animals in danger right now? They seem ok but we just got them on tuesday. If it is the stale air (I think it is because that weekend that ph went down to 7, once I opened the windows the 3rd period class checked the parameters and it went up to 7.4, then by the last period it was up to 7.8...we test 4 times a day...each class has to test for learning purposes and I do a morning before class and an afternoon after class to make sure they get close to my numbers) how do I help the tank get air. We have 2 wavemakers, one 50 gallon hanging on back filter and two 30 gallon filter-skimmer all in one combo units

Don't suppose there's any gas ovens or anything like that in the classroom?

 

[Icegirl]

No, baking soda boosts alk and lowers pH.

I suggest doing nothing until things settle down. Water changes are ok, but don’t expect much progress lowering alk that way unless you lower the alk in the new salt water, or do very large ones.

OK!!

 

[Icegirl]

Don't suppose there's any gas ovens or anything like that in the classroom?

Next door is the lab with burners