Any suggestions on how to lower PH

[MasonPonics]

Hello all I'm new to this site and joined cause I'm seeking information that is apparently hard to find. Quick back story is I've been reading up on aquaponics for over a year and built my first system roughly 4 months ago. My fish tank is 100gallons and the water comes from city water but in South Dakota that is fairly clean water, my grow bed is 50gallons and uses a River Stone media about a foot deep. My system started off well with decent plant growth and very rare fish (Yellow Perch) deaths, the system is currently in my basement which maintains a constant air temp of around 64-70 degrees in the summer and uses 2 large 48" growlights.

Now that some of the spec's of my system are out there my problem is with a HIGH pH, now videos and other sites pretty much all explain how to make low pH systems higher but rarely the opposite. Before I built my system i tested my tap water which read 7.8 then with rocks in it which was basically the same and hoped it would lower itself to 7 or so over time. Now 4 months later my system has been running and my plants start off well then over time begin to yellow up or get brown which tells me Nutrient Lockout as a result of high pH. I've even bought a pH down solution for aquariums and over a week or so time emptied the bottle into the system and I haven't seen it budge. Now after thinking about it the area I live in is mountainous and has quite a few large Limestone deposits which could explain why water straight from the tap is already 7.6-7.8

I guess my question comes down to does anyone have suggestions on what to add to get my water level down and if anyone has suggestions for media that would be more pH neutral. I know Hydroton (clay pellets) is the best solution but I'm fairly sure my entire state doesn't sell it at all and to have 12 40L bags delivered is insanely expensive + $20-$30 a bag.

Any help or suggestions is highly appreciated, I'm really aiming to revamp my system before the heavy SD winters coming baring down in less then a month.

[keith_r]

in my humble opinion, a ph of 7.6 to 7.8 is NOT a problem..
my system with yellow perch and bluegill ran fine at that level for at least 8 months. i moved indoors and reconfigured a bunch of stuff, and stopped testing for a bit.. when i measured the ph again, it was in the low 6's (about 2 months after i moved everything inside)
I've been buffering up the ph a bit with crushed shells (egg and sea)
i seldom saw any nutrient deficencies after the system matured a bit, and only used liquid "Maxicrop with iron" sparingly and occasionally. i just finished a 1 liter bottle i bought last april!

you can check your media by putting it in some vinegar, if it bubbles it's not good and will raise your ph.. i used mostly "river gravel" from home depot, but topped off my gb's with hydroton

[MasonPonics]

Ha, that's crazy you mentioned that media test, right after i posted this i filled two jars one with straight tap water another with tap water and a small amount if Vinegar. Without media in in it the water was 7.8 like i said and with Vinegar it was 6, then I put two of the river stones in each and am gonna let them set for a bit then test again to compare a before and after on both. I'll let ya know how that turns out.

My fish seem very happy but if it wasn't for the slow decline in plant health i wouldnt be so worried about it which is why I'm hoping its a pH problem and not some kind of other serious problem.

[keith_r]

what are your other readings? (ammonia, nitrite and nitrate) and temp?
my plants didn't do very well until i had more fish in the system, when i added 25 yellow perch to my 110gallon tank (that already had 15 bluegill, minnows and crayfish) my plants really took off, but i also had to add some filtration

[urbanfarmer]

Hello all I'm new to this site and joined cause I'm seeking information that is apparently hard to find. Quick back story is I've been reading up on aquaponics for over a year and built my first system roughly 4 months ago. My fish tank is 100gallons and the water comes from city water but in South Dakota that is fairly clean water, my grow bed is 50gallons and uses a River Stone media about a foot deep. My system started off well with decent plant growth and very rare fish (Yellow Perch) deaths, the system is currently in my basement which maintains a constant air temp of around 64-70 degrees in the summer and uses 2 large 48" growlights.

Now that some of the spec's of my system are out there my problem is with a HIGH pH, now videos and other sites pretty much all explain how to make low pH systems higher but rarely the opposite. Before I built my system i tested my tap water which read 7.8 then with rocks in it which was basically the same and hoped it would lower itself to 7 or so over time. Now 4 months later my system has been running and my plants start off well then over time begin to yellow up or get brown which tells me Nutrient Lockout as a result of high pH. I've even bought a pH down solution for aquariums and over a week or so time emptied the bottle into the system and I haven't seen it budge. Now after thinking about it the area I live in is mountainous and has quite a few large Limestone deposits which could explain why water straight from the tap is already 7.6-7.8

I guess my question comes down to does anyone have suggestions on what to add to get my water level down and if anyone has suggestions for media that would be more pH neutral. I know Hydroton (clay pellets) is the best solution but I'm fairly sure my entire state doesn't sell it at all and to have 12 40L bags delivered is insanely expensive + $20-$30 a bag.

Any help or suggestions is highly appreciated, I'm really aiming to revamp my system before the heavy SD winters coming baring down in less then a month.

Assuming you got a GOOD reading from a GOOD test kit of some sort, it is possible that your rocks contain something called calcium carbonate. It will keep your pH in that range indefinitely (or until you exhaust the rocks in your system). You're going to have to stick with it. It's not a bad pH. What's your stocking density? Low I hope? If not, watch your ammonia/ammonium levels. Good luck!

The reason you don't see much about lowering pH is because it should naturally drift lower and lower.

[bcotton]

Personally, I do aquaponics more for the plants than the fish and i try to keep my ph just below 7. My expanded shale is supposed to be neutral but it appears to be buffered to about 7.8. I buy "ph down" from a local hydroponics store for about $30 a gallon. It's mostly phosphoric acid and the fish do not seem to mind it.

I add it in 30-50ML increments to my ~400 gallon system.


Brian

[urbanfarmer]

Personally, I do aquaponics more for the plants than the fish and i try to keep my ph just below 7. My expanded shale is supposed to be neutral but it appears to be buffered to about 7.8. I buy "ph down" from a local hydroponics store for about $30 a gallon. It's mostly phosphoric acid and the fish do not seem to mind it.

I add it in 30-50ML increments to my ~400 gallon system.


Brian

Gotcha. Then you will want to go closer to 6, but since you used expanded shale you are really up the creek without a paddle...

As we all (should?) know shale contains calcium compounds including calcium carbonate (commonly used to bring pH up). Unfortunately, shale is advertised and sold as an inert aggregate. I have some sample with me and was planning to do a "neutralization test" and post the video results for all to see. Don't get me wrong, having shale in your system and keeping your pH between that 7.2 to 7.8 at all times without doing ANYTHING can be VERY NICE. However, it's not what YOU want in YOUR CASE. That's unfortunate, and for the misinformation out there, I apologize on the communities behalf. Silly folklorist aquapons...

EXAMPLE (everyone makes this claim, do not blame the seller since the supplier is who passes this info... I think...)


What I don't understand is why it would blatantly state limestone is bad, yet shale is clearly made from the compression and heat over time of limestone... in other words, shale is made from limestone and maintains significant quantities of the same chemical compounds found in limestone... Am I crazy or does this make sense to anyone else?

I will conduct the experiment next week and record it for everyone. I hope at that point everyone will be clear on this seemingly obvious topic...

[davidstcldfl]

I will conduct the experiment next week and record it for everyone. I hope at that point everyone will be clear on this seemingly obvious topic...

First, I thought 'someone' had already checked this out...and I thought that 'maybe' being baked sealed it some how..?

Looking forward to your results UF....

[urbanfarmer]

I will conduct the experiment next week and record it for everyone. I hope at that point everyone will be clear on this seemingly obvious topic...

First, I thought 'someone' had already checked this out...and I thought that 'maybe' being baked sealed it some how..?

Looking forward to your results UF....

I am not familiar with the process of creating expanded shale. I thought it was similar to how they make activated carbon activated... high heat and some gas? Does the bake sealed mean they coat it or just what happens when it's heated and gassed? It may well create a layer of some inert compound on the outside, but it can't possibly be 100% and as soon as you have some exposure of the calcite to the water it will start reacting (albeit more slowly depending on the exposed surface area)... good eye David, good eye... hmmmmm.....

Only ONE guy at the conference said his pH hovers around 7 with the expanded shale (I swear he was planted), but everyone else mentioned the same 7.2-7.8 range and the water creeps up and up on its own... I should have brought you a sample box of the shale... I didn't even think about it...

[urbanfarmer]

SO, I DIDN'T WANT TO WAIT BEFORE I DID MY FANCY EXPERIMENT UNDER THE CAMERA

I threw a piece of the expanded shale into a glass with some table vinegar (5% acetic acid). It looks like I have bubbly soda in the cup now. There is clearly a neutralization reaction. One piece starting floating after a few seconds from the bubbles it's producing.

In my experiment I will use 10.8 molal hydrochloric acid. It will react VERY quickly and VERY violently and will be VERY cool, but this at least answers our question.



Stay tuned for the eye burning, skin corroding, media melting episode!