Interesting problem in classroom tank

[S.G.]

Hello and thanks for taking the time to read my post.
I am new to reefing. My wife teaches kindergarten and someone gave us a tank for her classroom, so I am trying to learn everything I need to know as fast as I can.
It is a 210 gallon tank with a 90 gallon sump. All natural filtration. It has an algae scrubber and lots of macro algae in the sump. It has an eel, a pufferfish, powder blue tang, foxface, and moony. There are a decent amount of corals but I don't know yet what types they are. It has a Neptune Apex system.
So here's the problem: there are 17 5 year old kids and 2 adults in a relatively small classroom 8 hours a day, 5 days a week. The windows don't open, and the door to the outside needs to stay closed for safety reasons. So you can imagine how much CO2 builds up in the air. You can pretty much figure out when class is going on from the pH chart.
When there is no school for a few days the pH stays in a healthy range, usually between 8.25 and 8.4. But during a regular week, it usually doesn't have enough time to recover overnight so it's starting our in the morning at around 8 and going down to somewhere between 7.65 and 7.5, which doesn't seem so healthy. So I'm trying to figure out what to do. Some of the solutions I've seen about running air from outside don't seem like they would work because I don't have a skimmer.
Until yesterday it was being dosed 28.875 ml of alkalinity and calcium throughout almost the whole day. The calcium is at around 425 and alkalinity is around 8.5. I was wondering if dosing a little more, especially during the day, might help. I raised it to 35.2ml/day, only during the daytime, but I don't know if this will actually do anything or not. If anyone has any ideas or advice it would be much appreciated.
Thanks in advance for your help!

 

[FeatherstoneReefer]

There are many things that you can do. First I think that it is wise to go to your local aquarium store and try to find a used skimmer. Most stores have a section of used equipment or a stockpile in the back that they are just itching to get rid of. Secondly your PH is very important fro health coral growth and so on. I would suggest purchasing eight.four by aqua vitro and dose that every day. This will keep your PH at or around 8.4 all the time. If the than does not already have a lid, get one! those kids will destroy the tank

 

[S.G.]

There are many things that you can do. First I think that it is wise to go to your local aquarium store and try to find a used skimmer. Most stores have a section of used equipment or a stockpile in the back that they are just itching to get rid of. Secondly your PH is very important fro health coral growth and so on. I would suggest purchasing eight.four by aqua vitro and dose that every day. This will keep your PH at or around 8.4 all the time. If the than does not already have a lid, get one! those kids will destroy the tank

Thanks so much for you reply.
About the skimmer, the tank has been up and running the way it is for years without a problem, so I figure I will at least learn a little bit more before doing something like that.
Yes the tank is covered.
Are you saying to dose that instead of alkalinity, or in addition?

 

[saltyfilmfolks]

Is there a problem with the tank except for the ph report?

 

[S.G.]

Is there a problem with the tank except for the ph report?

Not that I know of

 

[Mr.Asbury]

My tank is in a school, and I have the exact same problem. We are going to cover cell respiration & photosynthesis here soon and I plan on using my pH graph from the apex during that discussion. I am waiting for the air line to arrive (hopefully tomorrow) to build this: https://www.reef2reef.com/threads/an-easy-way-to-increase-your-tanks-ph-with-a-co2-scrubber.57609/ to attach to my skimmer. I was able to order all the parts for ~$20 and the reviews on the thread linked seemed to all support the claim that it helps a good bit with the issue we're experiencing. I'll let you know how much of a change it has once it's up and running, and I'll be following along in case anyone else has some good advice!

Here's my "before" pH range, I'll update with the after once the scrubber's been running for a few days.

Here's the "after" picture. CO2 Scrubber linked above was added in the morning on 10/20.

 

[S.G.]

I am very interested in the idea of a CO2 scrubber, and that post makes it sound easy. But I don't have a skimmer and I don't know if I want to get one at this point. Does anyone think it would work/be enough to hook up a regular simple aerator to a CO2 scrubber and just have it bubbling into the sump?

 

[solitude127]

How often are the lights on for the Marco algae in sump and the lights for the algae scrubber as well?

 

[saltyfilmfolks]

How often are the lights on for the Marco algae in sump and the lights for the algae scrubber as well?

That would be my first choice too.

 

[S.G.]

How often are the lights on for the Marco algae in sump and the lights for the algae scrubber as well?

The algae scrubber is hanging over the sump and there are 2 very bright purple/pink lights shining at the screen from both sides. I don't think there are any other lights in the sump. The person who had the tank before us in his house had those lights an opposite schedule to the main tank lights, but since it was going to a classroom, he suggested that keep them both on during the day and off at night. But anyway it's already set to go on if the pH is below something like 8.25, so I can't imagine that would be the solution

 

[saltyfilmfolks]

A large Refugium would be a good idea. Same as they inject co2 into planted tanks. The uptake of a turf scrubber is likely not as large.
But a diy co2 scrubber would work.

 

[S.G.]

Here's a picture by the way just so you can get a better idea. Sorry it's not the best picture. Everything is inside the stand

 

[Katrina71]

@Miamialum620

 

[S.G.]

But a diy co2 scrubber would work.

When you say that a diy CO2 scrubber would work are you referring to what I suggested with the aerator, or something else?

 

[saltyfilmfolks]

When you say that a diy CO2 scrubber would work are you referring to what I suggested with the aerator, or something else?

The down an dirty version of a scrubber is basically an air pump in the bottom of a bucket with holes in the top. Yes. But ya do need a VERY good micro bubble stone. Conversely you could use a tunze 9001 -9006 compact skimmer and pull air in from it.

 

[FeatherstoneReefer]

Thanks so much for you reply.
About the skimmer, the tank has been up and running the way it is for years without a problem, so I figure I will at least learn a little bit more before doing something like that.
Yes the tank is covered.
Are you saying to dose that instead of alkalinity, or in addition?

The product handles both Alk and PH

 

[Miamialum620]

Here's a picture by the way just so you can get a better idea. Sorry it's not the best picture. Everything is inside the stand

Wow that is a massive tank. I have a 32g bio cube in my high school bio class and also am relatively new to reefing. It’s been up and running for about a month and haven’t really had any major issues with regard to water parameters. My ph does run on the low side (7.8) but my LFS says it’s not low enough to be concerned.

 

[S.G.]

Another crazy idea I was thinking of trying is to make an algae scrubber to absorb CO2 from the room in general. I read that you can put algae in a bottle full of water and put an aerator through the cap into the water and that will absorb CO2 out of the air. Supposedly that's what nasa does to recycle oxygen in outer space ( obviously in a much more professional way). I just don't know if this would actually do enough to make a difference.

 

[saltyfilmfolks]

https://www.bulkreefsupply.com/brs-...MImJzV99H_3QIVHLbACh2NBwTBEAQYASABEgLAHfD_BwE


https://www.reef2reef.com/threads/an-easy-way-to-increase-your-tanks-ph-with-a-co2-scrubber.57609/

 

[Mr.Asbury]

I hooked up my DIY CO2 Scrubber in the morning on October 20. Here's my "after" results.