LFS using ACID to lower PH. WTF?

[Wulfy]

One of the local fish stores is using acid (not sure
but I think its Phosphoric?).

I know that adding acid will lower the PH but is this
a right way to do that. It sounds so wacky.
I cant remember anything I read anywhere that
its a done thing.

Is this guy a genius or a dangerous maniac.
His fish seem happy but he did imply he did
have a high turnover.

 

[Faramir]

That's what pH down is, IIRC - phosphoric acid.

It works - if you want tanks full of phosphate.

Thing is, phosphoric acid is only weakly acidic. It does not dissociate much, and it's only the dissociated H+ that contributes to pH. And, of course, the H+ that does dissociate will then have to overcome the KH of the water... granted this is ameliorated somewhat by the fact that the H+ being taken up in this way would force the equilbrium to produce more, but even so...

The upshot of this is you end up having to add a lot of phosphoric acid to lower the pH significantly. Not a course of action I'd choose. The algae would love it....

Of course, using peat filtration is doing exactly the same thing, but using tannic acid rather than phosphoric. The difference is the tannins are generally considered good news, unlike the phosphates.

I'm still shaky on water chemistry so someone feel free to correct any misunderstandings.

Quite frankly, it'd be more effective to use nitric acid. But by gum you'd have to be careful, wouldn't you, or you'd give a whole new meaning to barbel erosion

 

[VoodooChild]

Something like that can't be stable. You're either going to have a drop which is going to be very stressful to the fish (by drop I mean bottoming out) or it'll go down and then go back up with water changes unless you religiously apply the stuff.

 

[FishBait]

Faramir, are you sure pH Down is phosphoric acid or sodium biphosphate? I honestly don't know.

Also, I understand alot of people are warry of using phosphate-containing buffers as it may initiate algae blooms. My question is, is the remaining phosphate left after dissociation organic? If not, algae cannot use it. I'm also curious if inorganic phosphates can combine with anything in the water to become organic phosphates. I'm not super great at chemistry so if this is absurd thinking just lemme know

 

[Faramir]

Most aquarium water has a lot of dissolved organic compounds floating around. I'd be surprised if none of them could react with inorganic phosphate.

It's very difficult to get information on what's in these things - perhaps the companies fear that if they told us, we'd realise it wasn't the magic powder they were trying to flog us.

 

[FishBait]

I see, I just wasn't sure what what all was capable of bonding with free phosphate. Just having a bunch of compounds around and figuring out what could bond with what is the part of chemistry I really sucked at And I agree that determining ingredients for lots of the trade's products if frustratingly difficult.

 

[Aderynglas]

You've all got me thinking now, in the past I used "pH 7.5" to keep the water stable in my goldie tank but now I just use coral gravel. I always had a sneaky feeling that the "pH7.5" was just an expensive way of buying sodium bicarbonate and possibly a little bit of calcium powder. Was I right or is it something completely different?????

Anyway coral gravel is way cheaper and keeps the water very stable.