Backyard Aquaponics
A place to discuss aquaponics

G'day all, I'm thinking I have a media problem. I dropped the ph on my new system (not cycled) to 6.8. The next morning it was back up to 8.25. Would this be the gravel I'm using or is it because it isn't cycled up. Thought it strange for the ph to rise like that. I used hydrochloric acid to adjust. Any ideas on the above would be appreciated. I did do the vinegar test which seemed ok at the time.

Sharpie, if it's a new setup, that's not an unusual pH.

Don't mess around with the acid - the pH swings that you create by adding acid do more damage than a constantly high pH.

It will come down over time - mine took about six months, and there is little to nothing that you can do to speed it up (without doing more damage than it's worth).

Patience is going to be the hardest thing here.

Thanks chilli. I guess I'm a little sus of my rocks. Did have a slight bubbling when I put some in hydro acid( one rock which was whitish in color so naturally think calcium/MgO)
It's very hard to no these things as a newbie, nothing like experience I say. Still preparing for a bed change out though:(

Hi Sharpie,

If any of your gravel contains carbonates it will be very obvious in the vinegar test, there will be constant streams of very fine bubbles rising directly from the suspect piece of gravel.

Being born and bred in Karratha I know that the water used to have excessively high amounts of Calcium carbonate in it, especially back in the old days when it was sourced from Millstream. Even the water from Harding dam contained high amounts, just not as much. I don't know how true it is, but a friend that was a long term Karratha local told me that the water is now filtered to remove Calcium, and if that’s the case, there should be far less carbonates than in the old days…

...anyway, Calcium carbonates in the source water may be what's causing your pH to bounce back up. Any acid you add to the system will consume the carbonates and dissipate as it does. Within a few hours the acid will have been depleted and the pH will rise back to what it was beforehand. The amount of acid required to consume all the carbonates in the water and keep the pH stable in the low 6's will be quite substantial, way too much for any fish to handle.

If there are fish in the system already, then you don't want to drop the pH by more than 0.2 or 0.3 in any one day... and you definitely don't want to keep bouncing the pH up and down. In that situation you are better off just treating any top up water with acid to a pH in the low 6's for 24hrs prior to adding to your main system, over time this will reduce the amount of carbonates in the system water and the pH should begin to drop naturally as acid is constantly produced by the nitrification process.

If there are no fish in the system you could try adding acid on a regular basis, enough to bring the pH down into the low 6’s, then retest the water every few hours and keep adding more acid, to keep the pH down around the low to mid 6's. Do this until you find you are having to add less and less acid each time to have the same effect. This process will have consumed a good portion of the carbonates in the water.

Don’t go silly with the acid though, you don't want the pH too low during cycling, the bacteria prefer a higher pH and they also require some carbonates supposedly. If after treating the water with acid for a few days you can get it to stabilise around 7.0… that’d be alright.

Alternatively, as described previously, leave the pH at 8.2 and just treat your top-up water, then see what happens over the next few months with nitrification and top-ups. However, I’ve had two AP systems where the pH has simply refused to drop below mid 7’s… one current system is over 18 months old and still sits around 7.4-7.6… even with treating top-up water with acid first… but it used to be even higher before I started doing that… around 8.0

One of my customers had a similar situation, where after 12 months his system pH still hadn’t begun to drop as everyone said it should, so for a few days, between batches of fish, he treated the system with HCl acid and kept the pH in the low to mid 6’s... a couple of days after he stopped adding the acid his pH had risen slightly from mid 6’s to high 6’s, then stabilised. He added the Trout and everything was fine, within a few weeks he had to add limestone to his system to stabilise the pH.

Use your own discretion as to which approach you want to take, I’m not advocating either, just giving you a few ideas for your consideration. Most here on the forum advocate not tampering with the pH during cycling and letting it come down naturally after cycling, but on some occasions it just doesn’t… and if you have water with very high amounts of carbonates it may be worth considering reducing them a bit before you even start, it's easier and safer to do then as opposed to when you have fish in the system.

P.S. Just out of interest, how long have you been in Karratha?... are you a long term local?... I used to know a "Sharpie" up there many years ago.

Cheers.

Well thanks for that mr. Damage (perhaps you are an angels fan with a nick like that). I think we still have high levels in our town water. Local water ph is around 8.2. Very interesting your theory on the acid. I have asked two chem engineers what is going on and they couldn't answer with conviction. I think you would be correct with your theory and I shall give it a crack me things.

So even if there is some contaminates in the media, one could hope that as the system ages it will produce enough natural acid to compensate.
Thanks again.

Sorry local water ph is 7.8 not 8.2.

Sorry damage didn't read all of post. I've been up here for 6 yrs now.

Is it that obvious?...

If the media is only very lightly contaminated with the odd small piece of limestone then it may be possible, but it would probably take a considerable amount of time.

I would consider taking a good sized sample of your gravel, ie: a couple of big handfuls (ie: with your hands cupped together), spread them thinly in a large pyrex dish, or similar, in an inch or more of vinegar, then sit and watch. See what percentage, if any, of your gravel contains carbonates. If there's more than two or three small pieces in a couple of large handfuls, then I'd consider finding new gravel... that's just my opinion... in fact, myself, if I had the option of an alternative gravel that wasn't going to cost and arm and a leg... I'd change it if there was any limestone in there at all.

Its that obvious I guess if you are already an angels fan. Yep I reckon that's a great idea. I'll grab a couple of handfuls and test tonight whilst enjoying a cool one and listening to who rings a bell.

Cheers
Sharpie.

Sounds like a good plan!...

...and down here we'll be listening to "Comin Down"... coz that's what it's doing!... pissing rain and hail... destroying my newly replanted veg garden.

Oh crap. No good. I would suggest you switch to "after the rain" to help things along.

...or, dare I say it... "Waiting for the sun!"

...although IMO, if Doc ain't out front... they ain't the Angels and it ain't an Angels song!

You guys made these lyrics pop in to my head.

You're giving too much away now Faye!

If that clip's anything to go by, we now have a much better idea on how you spent (or mispent) your youth!...


Might be getting a bit ahead of yourself there though... looking at the sat' pic Charlie posted over on the Rain thread.

LOL. I even have a son that has taken a liking to Bob Marleys music, what the?
Yeah wishful thinking with the clouds gone, I actually went from listening to that to April Sun in Cuba, gotta love Dragon.