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It seems to me that pH moderation is constantly coming up as a  subject in just about every discussion.  Because it's such an important detail of all aquaponic systems, I thought that I'd start a discussion to let folks chime in on what has worked and what hasn't worked as far as controlling system pH.  I know that some of you will say that the subject has already been talked to death in other discussions, but I think that this will be a great resource for folks who don't have the time to wade through the other discussions to glean details.  So experienced aquapons (that means you- Aleece, Murray, Rupert, etc.), and anyone else with questions or advice:  let's make life easy for the newbies and share some pH knowledge.

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Andy, perhaps you should start a new discussion and detail the situation, your system, chain of events, water quality, and what seems to be going on with the fish. This way we could concentrate more specifically on your situation and see if anyone can help sort out what is going on with your dieing fish. Some pictures might also be helpful.

Andy Smith said:
I am still loosing fish at the rate of one every two days. I don't think it is the water quality. I think there is something else going on. Any Ideas of diseases that I could have picked up from the second batch of 3 in fry that I got from Blue Beyond. Andy
This chart shows the interaction, between the PH and how plants can use the available minerals/nutrients.

[IMG]http://i931.photobucket.com/albums/ad157/davidstcldfl/nutrienttakeu...[/IMG]

I first saw this chart, in a different forum. It was posted by 'Castaway'. I asked, if I could re-post it elsewhere. He said it wasn't his...he must of found it in a google search (?)

I wasn't sure where it would be best to post it.....it's a shame to be several pages back, some may miss it. I think it may help alot.

Sylvia...TC...do you think it should be some where else ? Fill freee to move it, if you do.
It's sylvia's site but pH seems to be a good discussion for the chart.

Hi guys. This chart has been floating around the hydro world for many years so I'd pretty much consider it public domain at this point. Good idea to post it!
LOL....I finnally got a chance to watch Murray's 'Secrets' dvd....there was that chart again !
Hmmmm.....I'm not sure if I finished watching all of the 1st one yet :-)
Yes, it is a well travelled chart....but it is a really good chart that shows just exactly how it works.

David Hart said:
LOL....I finnally got a chance to watch Murray's 'Secrets' dvd....there was that chart again !
Hmmmm.....I'm not sure if I finished watching all of the 1st one yet :-)
well Phewy! I've been using the 5 way dip sticks and an ammonia dip stick... have yet to get any sort of ammonia reading (maybe the barest little glimmer of ammonia is being registered)... definitely NO Nitrite or nitrate readings... system is about 3 months old now. I thought my ph was OK... dip stick showed very pale... well my hubby got out his pool kit and we tried that for a ph test...and heavens!! so pink it appears off the scale! uh oh! We have well water... no chlorine etc. Tested it out of the faucet - looks like 7.3 or so.. let some sit in a container for 4 days (no aeration, just glass container of water sitting for 4 days), tested that... and get a reading of 8.5 or so! ACK! That is also what my fish tank water is registering :-( My plants are growing, but are pale, yellowish and not very robust. I lose a fish now and then... though the fish are acting very frisky and happy, eating well etc... I just get a dead gold fish periodically. Now also have tiny baby tilapia and am losing a few of those daily - majority of them are acting quite healthy and active and eating well....
BUT I have this very high ph, and so-so plant growth (actually miserable plant growth compared to the plants in dirt garden). Everything I read indicates ph should drop over time... mine's rising. My media is hydroton and lava rock. My research has told me that both of these are neutral and should not be affecting the ph... (my test of water left standing in a container by itself, and water sitting with lava rock seems to support that as both waters yielded the same resulting ph... 8.5 or so)
I have a 300 gal rubbermaid tank for the fish, 3 growbeds (flood & drain) 1 is 4'x8'x12in deep and 2 are 3'x2'x 7in deep (2 small ones all hydroton, large bed is 2/3 lava rock and 1/3 hydroton). I have maybe 75 tiny tilapia and 50-70 goldfish a few koi, mosquito fish etc.... koi and goldfish growing fast!)
I need some advice please as to what I ought to do to mess with the ph.... the standard mantra of *ph will naturally lower over time* does not seem to be applying. Help please.
Lori,
Those Dip strips for testing water quality are not thought very reliable. If you can, I would urge you to get yourself a freshwater master test kit that uses the test tubes and drops to test things. They are much more accurate and reliable.

The high pH is likely not hurting your fish, most fish like the higher pH so long as you don't have any ammonia. Hi pH coupled with ammonia and high temperatures are bad for fish though.

Is there anywhere in the system where algae is forming or growing? Keep in mind some types of algae are not very green. I've had brown string algae play havoc with pH on me before.

Now lava rock is generally neutral but if it wasn't well washed before going into the system, it is possible there could have been sediment in it that might buffer the system pH for quite some time.

Once you can confirm that your system is indeed cycled (with an accurate test kit) and make sure that algae isn't affecting your pH, and also that there isn't anything else in the system buffering the pH, then you might think about adjusting the pH. In the mean time, some chelated Iron can help the plants since they are probably suffering Iron lock out due to the high pH. Or you might foliar feed the plants with an iron spray according to the directions.

Lori Platt said:
well Phewy! I've been using the 5 way dip sticks and an ammonia dip stick... have yet to get any sort of ammonia reading (maybe the barest little glimmer of ammonia is being registered)... definitely NO Nitrite or nitrate readings... system is about 3 months old now. I thought my ph was OK... dip stick showed very pale... well my hubby got out his pool kit and we tried that for a ph test...and heavens!! so pink it appears off the scale! uh oh! We have well water... no chlorine etc. Tested it out of the faucet - looks like 7.3 or so.. let some sit in a container for 4 days (no aeration, just glass container of water sitting for 4 days), tested that... and get a reading of 8.5 or so! ACK! That is also what my fish tank water is registering :-( My plants are growing, but are pale, yellowish and not very robust. I lose a fish now and then... though the fish are acting very frisky and happy, eating well etc... I just get a dead gold fish periodically. Now also have tiny baby tilapia and am losing a few of those daily - majority of them are acting quite healthy and active and eating well....
BUT I have this very high ph, and so-so plant growth (actually miserable plant growth compared to the plants in dirt garden). Everything I read indicates ph should drop over time... mine's rising. My media is hydroton and lava rock. My research has told me that both of these are neutral and should not be affecting the ph... (my test of water left standing in a container by itself, and water sitting with lava rock seems to support that as both waters yielded the same resulting ph... 8.5 or so)
I have a 300 gal rubbermaid tank for the fish, 3 growbeds (flood & drain) 1 is 4'x8'x12in deep and 2 are 3'x2'x 7in deep (2 small ones all hydroton, large bed is 2/3 lava rock and 1/3 hydroton). I have maybe 75 tiny tilapia and 50-70 goldfish a few koi, mosquito fish etc.... koi and goldfish growing fast!)
I need some advice please as to what I ought to do to mess with the ph.... the standard mantra of *ph will naturally lower over time* does not seem to be applying. Help please.
I am beginning to get algae growth in the fish tank and on the pipe openings where the water enters the growbeds and returns to the fish tank. It has finally gotten warm here and water is no longer diving down to the 50s at night, so, yeah. Getting some algae. Does algae affect the ph??
We washed the lava rock pretty well - it was rained on for 2 weeks straight, then we rinsed it a lot when we put into the GB... water ran clear when we hooked it into the system.
As for cycling... I'd think it was all cycled... however I have yet to have any Nitrite or Nitrate readings on my test strips. The test strips DID register nitrates in the water that the baby tilapia came in.... I added that water into my tank hoping to do some good :-) But so far - I have lots of fish, but apparently pretty *empty* water. Seems a bit weird to me
Hi Lori,
It takes time for the NITRITE and then the NITRATES to show up in the system...as the saying goes, "it won't happen straight away. but it will happen" Watch the ammonia during the "cycling" stage . Make sure it does not get too high.
It is not uncommon to have algae in systems especially in the early stages. Keep direct sunlight off the water and that will help to limit algae growth. Small amounts of algae will not influence pH , but algae takes up oxygen and nutrients which we do not want to happen in an aquaponics system.

Lori Platt said:
I am beginning to get algae growth in the fish tank and on the pipe openings where the water enters the growbeds and returns to the fish tank. It has finally gotten warm here and water is no longer diving down to the 50s at night, so, yeah. Getting some algae. Does algae affect the ph??
We washed the lava rock pretty well - it was rained on for 2 weeks straight, then we rinsed it a lot when we put into the GB... water ran clear when we hooked it into the system.
As for cycling... I'd think it was all cycled... however I have yet to have any Nitrite or Nitrate readings on my test strips. The test strips DID register nitrates in the water that the baby tilapia came in.... I added that water into my tank hoping to do some good :-) But so far - I have lots of fish, but apparently pretty *empty* water. Seems a bit weird to me
Lori,
I fear your test strips may be suspect since you mention that they were reading a different pH than the other test you did.
I would definitely get some more accurate tests to check and see if your test strips are telling you the real story.

In my system with high pH, my nitrates tend to be rather high because the plants struggle to take up the nitrates.

My well water is high pH water from a limestone aquifer. It does take time for the bio-filter to use up the excess buffer in the water but it can happen. I did use some sulfuric acid (pool acid) to reduce the pH of some of my well water but it did rebound back up to 7.6 for a time until the bio-filter used up more of the buffer capacity. Since you have fish in the system, I don't recommend that you go adding lots of acid into the system directly. I would recommend you get a barrel and do some pH adjustments to your well water so you can experiment to see how much acid you need for a given amount of water and then leave it to bubble overnight and measure again to see what the pH is. Then use the pH adjusted water to do top ups to the system so you can very slowly adjust your system pH. If you go putting too much acid into your AP system with fish and plants you might cause a complete crash or if there is something in the system buffering the pH some how, you could cause some major pH bouncing which is also pretty bad.

So, once you sort out your testing.

Then you can experiment on pH adjusting some water before you use it to top up or do small water changes on your system to slowly adjust the pH of your system till you get it down close to 7. It is best to move very slowly going only a point or two a day since the fish, bacteria and plants will all have to adjust to the change.
Thanks Aleece and Murray. I appreciate you jumping in here. I've ordered the API master test kit - I actually don't think the strips are faulty so much as they did not go high enough! HA! I've also done a quick experiment on the water to see what/how much vinegar will do... looks like 1/2 to 1 cup of vinegar in my 300 gal would be approp (in order to make only very small changes :-).... however I will wait and continue to just let it be and see what happens for a few more days.

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