Aquaponic Gardening

A Community and Forum For Aquaponic Gardeners

I am picking up an AP running system this weekend.  I got a deal and grabbed it before i had time to learn much about APs.  i was told there is a way to raise and lower PH organically like vinegar and baking soda.  anyone have info on how to do this and what to use?  also, a friend gave me a PH tester they had for their pool.  will that work to test ph and chlorine (i'm trying to off-gas chlorine for when we pick up the AP system this weekend) or do i need to go to a petstore or somewhere?  anything else i need to get and be testing?  thx! 

Views: 1796

Reply to This

Replies to This Discussion

I have a very high pH, about 9.0.  The water from the hydrant is very close to this also.  I have lost 12 of 26 catfish. Everything else is in balance.   What should I do?

Lowering a water's pH is not as simple as folk make it out to be. Some folk have a very easy time while it is more difficult and costly for others.

Before answering your question, you must understand alkalinity. Alkalinity is the measure of water's ability to resist changes to acid. A "buffer", in our context, is most often referring to the alkalinity. The marketing shorthand nomenclature slang for alkalinity is "KH", which "KH" has an entirely different meaning except it mostly relates to alkalinity. Personally, I prefer the term alkalinity rather than "KH" unless I want to be lazy. Alkaline and alkalinity is not the same. Alkaline is describing the water's pH when it is above 7.0. Alkalinity is describing the measurement of the water's ability to resist changes to acid.

To better understand how, a water "buffer", or alkalinity, function, then think of a mattress pad. When you jump on the mattress pad, the pad slightly lifts you back up due to the springs in the pad. The springs act like how the buffer functions. Each time you aggressively jump on the mattress pad then the springs get worn out and don't lift you up so much. The mattress pad is the "water", the pad's springs are the "buffer", and the jumping is the acid. Thus, as you continue to aggressively jump on the mattress pad (that is adding "acid" to the water) on the springs (or "buffer"), then the jumping (or "acid") eventually wears out, or depletes, the springs (or "buffer"); so, then, you eventually have to add more springs (or "buffer").

This explains why folk experience the occurrence of "pH jumping" whenever trying to lower water's pH. Lets say your water's pH is 8.4. When you add an acid, the water's pH will absolutely drop to say 7.8 pH. However, if the water's alkalinity is high, then after some agitation and a few hours of allowing the acid to dissolve into the water, then the pH jumps back up to 8.4 pH. This becomes extremely aggravating to folk when they don't understand why this is happening. However, if your source water's alkalinity is low, then the degree of this pH jumping is reduced or not even noticeable.

Vinegar, lemon juice, and peat moss work fine to lower the pH as long as the water's alkalinity is low. If your source water's alkalinity is quite high, then you will have to use a tremendously large amount of vinegar, lemon juice, or peat moss, which costs money and time.

Rain water, that is preferably filtered through a carbon filter, is your cheapest and safest bet. However, if it does not rain enough for you to harvest enough of it, then you will have to look into hauling or shipping in distilled or deionized reverse osmosis water. There are filtration systems to create deionized reverse osmosis water, but the filters can become costly. This is where the much much stronger acids come into play.

This is why knowing your source water's alkalinity is quite important, amongst various other reasons. You find this out with a "KH test kit".

Personally, to keep this easy, while you are doing your school homework reading to better understand this stuff, my advice for you is to be happy with your water's current pH. You might be one of the lucky ones where the number of fish will be sufficient enough to lower the pH.

To lower the pH, first use rainwater, if you have access to it. You can try some vinegar or lemon juice or even peat moss, but, as explained above, do not become disappointed if you have to use a large amount.

To raise the pH, do not use baking soda. There are very many options to accomplish raising the pH. The aforementioned thread, referenced earlier in this thread, Bringing up pH levels in your aquaponic system - Bright Agrotech, does a decent enough job at giving an answer.

Thanks for the info! Tells me a lot. I live in a severe drought area and am not set up to catch rainwater. It will be early next year before that changes. My tank is 275 gal. When I got the fish everything looked good including the pH. I don't really understand how it got this far out of whack but will probably just suffer through. I can't get catfish until next May so I have a while to figure it out. Thanks again.
Thanks for the info! Tells me a lot. I live in a severe drought area and am not set up to catch rainwater. It will be early next year before that changes. My tank is 275 gal. When I got the fish everything looked good including the pH. I don't really understand how it got this far out of whack but will probably just suffer through. I can't get catfish until next May so I have a while to figure it out. Thanks again.

Actually, my post was meant for this thread's author. that is Ms. Romen.

For you JoAnn, if your pH is as high as 9.0 and you are confident that this is an accurate pH reading, then this might possibly indicate a calcium deficiency. I am talking about calcium deficiency in the water rather than in the plant. In a carbonate/bicarbonate base buffer system, which most water is this type of buffer system except particular other areas in the US of A are more phosphorus based, calcium is the divalent cation that prevents the pH from rising above 8.4~8.6.

So, you can try adding a calcium sulfate (1.6 ounces per 100 gallons). First dissolve then in a separate container very good then add it around the tank. Wait 12 hours. Then test the water's pH to see if it dropped below 9.0. If no go, then do another dose, but no more doses after the 2nd dose.  This method will only work to reduce the pH to down around 8.6 and no lower, that is assuming the cause of the high pH is the abundance of carbonate (CO32-) since free calcium (Ca++) has an extremely strong attraction to free carbonate so to create the precipitate called calcium carbonate (CaCO3).

However, the high pH could be the result of city water treatment or other water products or garden additives that could have been dosed in the tank. So then, all you can do is to dilute the water with rain or deionized reverse osmosis water or some other acid so to burn off the carbonate. When carbonate (CO32-) is burned with an acid, then it creates carbon dioxide (CO2). This is why gravel fizzes whenever you add vinegar to it; the fizzing is the releasing of carbon dioxide as a result of the vinegar counteracting a particular formation of carbonate on the rock.

how r y'all on pH?  r u adding more acid each time u fill your tank or sporadically?  I never got my pH where it's needed to be since I started in September.  folks said go slow so i sure am.  lol.  with so much evaporation it seems it'll be really hard to get it right now in the summer.  have u seen growth differences when your pH was adjusted correctly?

r catfish more sensitive to high pH?

Stephanie, i read baking soda can increase pH.  hoping it doesn't get into my system much from spraying veggies on the grow beds.

Charles,

Where would  I get calcium sulfate?  I have checked the pH at least twice a day for about a week ( when the fish started dying).  I have also checked the city water's pH.  Last night I ran the city water into  the garden for a while just in case there might be something in the pipe between the city and the garden. It was between 8 and 9 every time I checked. Three more dead fish since yesterday morning.  I do have some slime on the sides of the tank but the water is clear.  I do appreciate all the help and advice.

My city water's pH is 8.2. I always have to add aquadown ph reducer after adding water. My tank & sump total 140 gallons, and I have to replace 20 gallons every 4 to 5 days. One good thing- the city puts carbonates in the water.

Calcium sulfate is just Gypsum, which is easily found in any garden section. If this does work, then keep in mind it will only lower your pH down to around 8.4~8.6.

If you need it lower, then you need to treat a separate container of tank water with an acid, agitate this container good for a few hours, then slowly add it around the tanks parameter. Then do this again every 24 hours until your desire pH is obtained. For the acid, you can try vinegar or lemon juice or even peat moss, but, as explained above, you might have to use something stronger.

JoAnn Dobson said:

Charles,

Where would  I get calcium sulfate?  I have checked the pH at least twice a day for about a week ( when the fish started dying).  I have also checked the city water's pH.  Last night I ran the city water into  the garden for a while just in case there might be something in the pipe between the city and the garden. It was between 8 and 9 every time I checked. Three more dead fish since yesterday morning.  I do have some slime on the sides of the tank but the water is clear.  I do appreciate all the help and advice.

Thanks. I will be in Lubbock, TX tomorrow and will try to stop by a garden place.

You are truly lucky.  Hard water is magic in aquaponics.  It's a blessing - count it! 

I would just wait a couple of months for your pH to come down naturally.  It'll happen at a good clip when it does (not dangerously fast, just surprisingly so after months of no change), so be sure to keep checking at least 2x/week.  If you want to see the drop coming, test your hardness with the API hardness test kit.

When it hits 6.5, do a partial water change (1/4).  After that, you'll have a stable (well-buffered) pH 7.0 or so. Partial water changes or replacing water for evaporation will keep it stable.

Jeremiah,

Thanks for posting.   Our water is very hard.  I hadn't even thought about it being the cause since it's something we just accept around here.

Reply to Discussion

RSS

© 2019   Created by Sylvia Bernstein.   Powered by

Badges  |  Report an Issue  |  Terms of Service