Aquaponic Gardening

A Community and Forum For Aquaponic Gardeners

Hey Everyone,

Does Lemon juice work to reduce PH in a system?

I bought some rock wool to start some lettuce seeds and the back of the package said to use lemon juice to reduce the water ph to 5.5 to start the seeds. 

I figured this would work in my system as well, which has been consistently coming up with a PH of 8.2, so I squeezed a few lemons into the system and tested the PH the next day and I noticed that the PH went down to 8. So I squeezed a bunch more lemons in. I put about 12 lemons worth of juice into my barelponic system, about 55 gallons of water.

I think the answer to my question is no, because my I tested the levels today, and my PH is still at 8, and all my other levels are weak. I'm about 2 months into cycling my system. My amonia already spiked and was consistently reeding 0.25 ppm, now its at 0. My Nitrites were reading 5ppm now they are 2 ppm and my Nitrates which were at 40ppm are now at 0. Did I just kill all my bacteria? Is all this lemon juice bad for the fish? 

I only have 2 gold fish that have survived the cycling. Should I add more fish? Should I change the water and start again? I have a lot of new growth in my grow beds right now.  is the lemon juice bad for the plants?

Views: 3618

Reply to This

Replies to This Discussion

Hello all,

IMO, "natural" pH remedies are mostly pretty ineffective. In an aquarium application, things like driftwood and regular water changes (replacing with pH adjusted water if nec.) are fine and work well. In an AP system, take care of your business with the proper tools. Use HCI or Nitric Acid and make subtle adjustment as to not throw your fish into pH shock (and kill them). Treat your top up water moving forward, but the most important issue is to understand why you are at 8.2 and try to correct it. If its a new system settling down, that's one thing. If you've got an established system that hangs at 8.2, well, something is fishy there :)

Ok, sorry, just read you're still cycling with a few goldfish. In that case, let nature take it's course - the system has other business to contend with before pH comes down on it's own. Mostly, goldfish, comets, koi and similar can handle the cycle just fine. It's actually encouraging to hear that your cycling with fish. I believe it's the best way to get your system running.

Hydrated lime, or Potassium Carbonate/BiCarbonate... will buffer pH up.... not downward...

Oops, you are right. I really shouldn't reply when I'm tired. Sorry all

Vlad, is tannic acid the only thing in wood that lends to lower pH. If so, then redwood ought to be a good option. I always thought it was the tannins in redwood that made it rot-resistant, so is that an issue for damaging the biofilter? And I'm not quite clear what you were saying about the iron chelation. Does the presence of wood reduce or increase the available ferrous ions?

As far as I know, tannins are the biggie for pH. 

Yep, redwoods are a great source of tannins, but the pitch (resin) that might tend to ooze out of them over time generally keeps aquaculturalists from using redwood or any other soft-wood. 

In humans, tannin chelated iron is totally bio-unavailable. In plants, tannin chelated iron is mostly (but not 100%) bio-unavailable (non-heme). So the presence of wood containg tannins could only reduce the bio-availability of iron to plants in your AP system.

Without splitting hairs or getting nit-picky, in practical reality, in an AP setting...seems highly unlikely that tannins would impact the bacteria in a significant way.

Thanks Vlad, Appreciated. Unless tannins can alter plant-usable iron chelates, I don't see how they could "reduce" the available iron. In fact, I'm still a bit confused on the whole iron cycle in aquaponics. According to Rupert, iron is seldom in short supply in aquaponics as long as pH is low enough, and I assume he means bio-available iron. Rupe says chelated iron is needed in higher pH systems because it can be absorbed by plants regardless of pH (within reason of course). Mary, I believe, has experience where two identical systems differed only in that one had driftwood in it, the other did not. The one without sufferred iron def, and was corrected by simply adding driftwood. My original system started at pH 8.2 (that's my well water), and settled to 7 in time. Now all my tanks are high, from 7.6-8.2, and I am suffering from iron def for the first time. Perhaps I should start a specific thread on the matter. Sorry Mary and Rupe if I have misunderstood you or even mistook whom I attributed the experience/advice. I shouldn't be so lazy.
Got it, Vlad, thanks. That all makes perfect sense, an I wasn't reading more into your advice than stated, I was just unclear how tannins would reduce bioavailable iron. Thanks again, friend. On the subject, I also ran across a reference that oak leaves are a good source of tannins and Rotifera as well. Some dried leaves contain up to 50% tannins. That could explain why my original system cycled nicely down to 7, because much of the gravel I used had a fair amount of oak leaves in it as well. Also interesting, I had some open-topped wading pools outdoors growing greenwater and blackfish (local minnows), and they became damn near filled with oak leaves after a rager of a windstorm a couple of months ago. I tried to remove the oak leaves, but the blackfish that where caught in the cleaning net thrashed wildly, and were damaging themselves on the sharp leaves, so I left it be. Then a week ago I cleaned out the whole pool, an was amazed to find all traces of the oak leaves were gone, apparently decayed and eaten by Rotifera, and then blackfish. I never did check the pH. I don't want to buy pH down if I don't have to, even if it is cheap and effective. It's just principle. This whole AP system needs to be sustainable offgrid to keep my interest in the long run. Since my water starts at 8.2, then something must be done. Perhaps a pre-soak of top-up water in a barrel of oak leaves will be simple and effective. Vlad, in your opinion, would a handful of iron in this oak leaf staging tank eliminate the risk of tannins consuming iron in the AP water?  Would the presence of iron in the oak leaf tank reduce the tannin's ability to lower pH?

No problemo buddy, I was in a huge rush, when I wrote that, was trying to cram, and wasn't directing that comment at anyone in particular.

Yeah, I think the word itself comes from the old German word for oak and/or conifer. And it's not just heartwood that contains the tannins. (Though we probably get caught up with driftwood because of the aesthetics). Leaves, unripened acorns (basically any plant parts that make your lips pucker is probably full of tannins. (I've tasted a green acorn before and it's probably akin to a little tannin-bomb :)...hehe that was totally unintentional...Tannenbaum...tannin-bomb. Anywhos...

I understand those principals and commend them. Pre-treating your top up water (whether with tannic acid or a purchased product) seems a bit 'safer' or 'controlled' (avoiding big pH swings for the fish, not potentially going to far etc)...

The handful of iron seems intuitively helpful, but probably not necessary in a muture system (like yours) where the fish are being fed decent feed. Remember that Terri's study showed us that (red) Talapia only capture on average 11.46% of the iron contained in the feed. The rest gets shat out into the system water. So even discounting your source water (in many places 0.05mg/L, or less, to 0.3mg/L, the upper legal for drinking water , in some places) your still putting in a decent amount of iron in your water. It seems reasonable that you'd fine without the 'handful of iron' in the tannin top-up.

Besides, keep the fish in mind. On the one hand...the plant biology side, iron seems the 'easiest' of the secondary/micro nutes to deal with. You cant really over do it (within sanity), and it doesn't seem to interfere with the uptake of other essential elements. 

But on the fish side, a given amount of iron that is fine at neutral or higher pH, is damaging at a lower pH, and deadly within days at a lower pH still. (Though I doubt anyone runs their system even near pH 5.5). Peuranen, Vuorinen, & Hollander,. Finnish Game and fisheries Institute 1994.

Though organic matter in the water (like in AP) seem to lessen this toxic accumulative effect.

Iron is turning out is anything but 'simple'. And the fact that it will form complexes quicker than Kate Moss at a smorgasborg, with just about anything organic isn't helping to simplify...

Almost all hydro literature I've ever come across tells us that you need 2-3mg/L to stave of Fe deficiencies in most plants. 

Almost all aquaculture literature I've ever come across tells us that 0.3mg/L or less, are the safe recommended max levels of Fe for fish.

So, something there is fishy. Anyways...sorry for rambling...

tannin-bomb?......... oh.

Sphagnum moss brings ph down naturally.

Haha. +1 for the Kate Moss reference (and tannenbaum). I'm laughing so hard I forgot what my question was. Now I suppose just try it and record the results.
Oh yeah, remembered my question. When do you sleep?

Recording how/what you do, observing, and recording those observations is always good. Having a written record to look back on while experimenting is really great sometimes. (Though can be tedious while doing it :)

Hehe...So you noticed...Yeah, I do keep some pretty weird hours when things allow. I'm a huge fan of the architect  Buckminster Fuller, and what he called Dymaxion sleep (basically just polyphasic sleep). You really can get so much more done in a day/night. (It's like being part lesbian). Problem is, everyone/thing around you is on a different schedule. A doctor friend once told me that my propensity for ployphasic sleep might have less to do with my personality or constitution, and more to do with the massive head trauma I was subjected to long ago (I actually got to be dead for a short time, really exciting). I don't know if I buy all that, but it definitely did shift my perspective on what is important, and what is not and how to (try to) best arrange the little time that we are given here. And not to waste so much time on what I generally like to call "stupid shit". Though since I'm not rich, avoiding spending time on some such "stupid shit" is unavoidable at times. Anyways...

Yep, sphagnum moss sure will bring down pH, but in Jon's case (if not all cases) the oak leaves are probably a more sustainable route I'm guessing.

Reply to Discussion


© 2021   Created by Sylvia Bernstein.   Powered by

Badges  |  Report an Issue  |  Terms of Service