Understanding pH.

[legrunt]

Hi everyone. I'm struggling to understand how pH works. Back in my soapmaking days, I was told that to determine the pH of a freshly made batch of liquid soap, do not stick your pH meter directly into the soap or you would (understandably) simply gunk it up. Instead, take a drop and dilute it in plain purified water. Then test the pH of that.

Layman me would simply think that diluting it that much would bring the pH closer and closer to 7 right? Apparently not.

So here, with regards to kalkwasser, I am facing the same conondrum. My RO/DI ato reservoir keeps building up some sort of bio film. So, taking my experience with the soap water, I was thinking of putting in a bit (like, 10-20ml) of kalkwasser into my RO/DI to raise the pH enough to keep any bio film from building up. Think that will work?

But at the same time, I'm wondering about the longevity of my ato pump... I've read that continuous soaking of the pump in fully saturated kalkwasser is hard on the pumps and cause them to fail prematurely... Would soaking them in my highly diluted solution have the same effect?

Thanks!

 

[Randy Holmes-Farley]

There are many questions here. For a discussion of the science of pH from a reefkeeping perspective, this article is a good place to start:

pH And The Reef Aquarium
http://www.reefedition.com/ph-and-the-reef-aquarium/

On some of the specific questions, dilution does not always bring pH closer to 7. Seawater is a remarkable example. Adding pH 7 fresh water to seawater at pH 8 raises the pH above 8 (very slightly). The reason has to do with the bicarbonate in the seawater, which becomes a weaker acid as the seawater is diluted.

Some calcium hydroxide will raise the pH and prevent bacterial growth in the ATO. The pH of kalkwasser doesn't hurt most marine-intended devices, but there can be some that may be damaged. 10-20 mL in an ATO likely won't be enough

What pump do you have? Are you otherwise using kalkwasser?

What type of water are you putting in the ATO?

Is there a specific reason to be concerned about the bioflilm? I doubt it causes any harm and I'd personally ignore it.

 

[Ron Reefman]

I'm wondering why you are getting a film in your ATO reservoir? I use a 20g aquarium for my ATO, and I made a lid for it. But it stays clean and I never have any film in it.

 

[legrunt]

I'm using a simple water container for my ato reservoir. I think it holds 3-4 liters max.

20ml in a small container like this won't help with the biofilm? I'm using straight RODI in my reservoir... Now with a small amount of kalkwasser mixed in.

I dunno if I'm just being *nal about the biofilm... It just feels "yucky" when i wash it out. I guess if there's really no impact to anything, i might need to learn to be ok with it...

As for kalkwasser, I've just started dosing it from a simple diy solution, using a coke bottle.

In that bottle is saturated kalkwasser, going through an auto doser. Right now it's dosing 1ml each hour, so I'll test daily and keep increasing the dosage until i get my alk stable.

 

[Hilltopreef]

Seems enough light is getting through the transparent container and letting algae grow on the walls of it.

 

[Bnichols124]

Whats the tds or phosphates of your rodi water

 

[legrunt]

Hmmmm... I didn't think of that.
I could spray it black, but then I'd have to peer in through the top to see the water level remaining.... Hmmmm hmm hmm

 

[legrunt]

Whats the tds or phosphates of your rodi water

Tds is zero, but i never tested phosphates, assumed it would be zero too? Brand new ro membrane and di resin...

 

[Randy Holmes-Farley]

Why not just ignore the algae?

I'm not sure why you picked 20 mL.

20 mL of saturated limewater with a concentration of 0.0408 M OH- added to 4 L of fresh water will dilute the OH- to 0.0002 M. That will have a pH of about 10.3.

There are microorganisms that will grow at that pH. WIl it help in your case? maybe, maybe not.

Be sure the plastic is not polycarboante. It will eventually degrade at high pH.

 

[legrunt]

Why not just ignore the algae?

I'm not sure why you picked 20 mL.

20 mL of saturated limewater with a concentration of 0.0408 M OH- added to 4 L of fresh water will dilute the OH- to 0.0002 M. That will have a pH of about 10.3.

There are microorganisms that will grow at that pH. WIl it help in your case? maybe, maybe not.

Be sure the plastic is not polycarboante. It will eventually degrade at high pH.

Wow, that's the detailed answer i was looking for, thanks so much!

I chose 20ml at random...

 

[Hilltopreef]

Try covering it with a towel.