Aquaponic Gardening

A Community and Forum For Aquaponic Gardeners

pH continually dropping to 5... What the heck is it??

My system is 6 months old and the pH has been dropping since day 1! I can't figure it out and it's driving me bonkers. No dead fish, no dead spots, I even replaced a bed that had pond-liner cuz I thought it might be the culprit. Nope, still dropping! It wants to go below 5! Plants seem happy, I get great squash but mushy tomatoes. And a gigantic pumpkin that is very happy. Fish seem fine as they are eating and making babies, but the fry will die if it gets too low.

Water out of the tap is fairly hard, and 8.3 (after sitting a few days in a barrel). I also have a breeding tank (no plants) and pH stays right around 8. But in the outdoor AP system, it drops. I even have 30lbs of crushed coral in the beds and sump. At this point I'm adding a tablespoon of pHUp almost every day. I've read tons of posts, been patient, but I'm at my wit's end. Help please!

Here's the low down:
CHIFT PIST System
275 gallon Fish Tank
with 30 6" fish and usually some fry
60 gallon sump
3 Growbeds 4'x4'x12" with Hydroton

Temp is 74
Ammonia .25
Nitrite 0
Nitrate 0-5 (closer to 0)

Any ideas? Could it be the Hydroton?

Views: 1657

Reply to This

Replies to This Discussion

I hadn't thought about river rock. I may do some more research on that if the shell grit doesn't work out.

On a chemistry note.....could total alkalinity and calcium hardness have anything to do with the lack of buffering capacity I seem to have in my system? I tested my water with a Taylor test kit and got this:

Tap Water: TA - 100ppm, CH - 50ppm

Tank Water: TA - 10ppm, CH - 310ppm

Obviously my calcium carbonate and potassium carbonate additions along with the tendency of the system to acidify have changed to chemistry of the water, but it has been so long since I took chemistry I am having a hard time wrapping my head around what the above numbers tell me about what is happening in my tank with the daily pH drops and what effect I am having with my additions. If I could figure that out I might be able to manage my pH better. Is there anyone out there that can explain the above in terms of consistent daily pH drops of 0.2-0.4 pH units two months after the completion of fishless cycling? I'll keep trying to figure it out myself too and check other discussions. If this is the root cause for me, could this possibly be true for Dagmarvelous as well?

Sure, why not?  I guess the natural flow of conversation which is sure to lead to other places in time took me to this point.

Harold Sukhbir said:

Hi Tradewind,

May i suggest, if you'd like we can carry the discussion of your system/issues to a separate post/topic, which can be dealt with in detail. This way we won't color/distract from the information coming out of Dagmarvelous's discussion.

Tradewind said:

I was wondering if I was feeding my fish enough. Frankly, that might be a major contributor to the problem.  When I was bringing my system through cycling I did fishless adding a cap or two of ammonia.  It was very easy to regulate and I cycled in about 4 weeks.  My ammonia would be back to zero the next morning with zero nitrites and a boat load of nitrates.  I am wondering if my little fish are putting enough into the water to do anything.  Perhaps the little ammonia I am seeing is due to fish kill which seems to be pretty normal for these Shiners.  They really do dislike 97 deg water.   But they have lived considerably longer than I was told they would by the guy that sold them to me.  I still have about 20 of the little guys in there.  I was thinking maybe a should feed them a bit more.  They boil the water when I do sprinkle a little food in there and it is gone is just a few seconds.

Here is the rule of thumb I was told and it seems to hold true with large amounts of tank water say 75 gallons and up. I put this in my system which is about 1200 gallons with the beds, sump and fish tank. I used 1 cup to every forty gallons of water. It took it about 2 weeks to level off and then runs between  6.8 and up to 7.0 and never changes and  is has been like this for 6 months and running for me. I noticed the ph starting to drop when the mesh bag gets covered up with alage. My system is 2 1/2 years old and I got tired of putting calcium and potassium in all the time. Now I just add some potassium when the plants look like they need it and iron and that is all I have to do.

The rule of thumb is this add 1/4 to 1/2 cup of crushed coral per 20 gal of water. Always put it into a mesh bag so you can take it out if something goes off with the levels you are trying to achieve. The Friendly’s Aquaponics also came to the same conclusion with using coral sand in their systems it seems to level itself off depending how much calcium is needed. Here is what some fish keepers had to say about the coral.

 I think there are some misconceptions about using buffers and crushed coral especially.  Unless you are creating an acidic environment specifically by injecting CO2, or using peat, etc. there is only a small amount of the material that will dissolve.  The dissolution rate is dependent on the pH and the amount of cations available in the water.  As the pH and KH goes up due to the dissolution of the coral, the solubility decreases, so unless you are injecting CO2 (and even if you are) the amount of coral is irrelevant, if it's in the filter, because you are pushing water past it, and all that will dissolve, will.  If it's sitting in the substrate or bagged in the corner, it might make a bit of a difference as you're not moving as much water past it.

 

Thanks for the rule of thumb! I have definitely been erring on the side of caution and have not added enough shell grit if that is the addition rate. Here's hoping that it will stabilize things a bit!

Just keep it in a mesh bag and monitor the levels for the next month and if it changes to much just pull the coral out. Otherwise I think you find it much easier to work with the coral after it levels off for you.

 

Casey, you bring up a great point.  I'm going to buy an Alkalinity test kit and look at my numbers.  I borrowed a kit when I first started out and I could never get it to read correctly; that is, it seemed to work when I tested my tap water, but couldn't get a reading when I tested my tank.  Figured I was doing it wrong and gave up.  Now I'm thinking that it could be the key to the whole problem...

My coral numbers are measured in pounds, not cups... so I have no idea how much I have in there.  Will pull out the mesh bag and get a guesstimate.  My gut says I'm nowhere near the "rule of thumb" that Wes gives.

Hey you can go here online and get the API Master Freshwater kit for only 19.99 This is were I get mine.

http://www.bigalspets.com/freshwater-master-test-kit.html

Oh make sure you coral is under your running water, if not you wont get the same effect and could take much longer.

 

Wow, thanks Randall!  Is it really that simple??!  I'm in Orange county California (read: Suburbia!) and when peeps started talking about river rock, I thought they were really going to their local river and pulling out rocks! (ya never know with AP!!).

Can I put it in the sump, under outflow of the growbeds so that water passes over it?  Or does it have to go directly into the growbeds?

You can also go to your local landscape rock supplier and get rocks really cheaply in bulk. They should also be able to tell you the composition of the different types of rock they are selling as well and whether they are pH neutral or not.

I would think rocks would be harder to deal with than shell grit though, especially if they are in the grow bed where they might be harder to remove if the effect on the system were to be too much......the sump might be a good place though in a mesh bag....

I am hopeful the shell grit will work for me now that I know how much to add. Thanks again Wes!

I'd be curious to know how everything works out for you Dagmarvelous! Good luck!

 

I am new at this AP game and sometimes I get concerned over the advice I receive.  Just as surely as you will get one opinion someone else will give you a conflicting one.   Life can be frustrating on its own without the help of others.   No license is required to give advice therefore one could be suspect of anything anyone says even those who are considered authorities as I have seen them disagree.  That being said, I always welcomed advice and believe it is up to me to sort it out.  On this thread there have been several recommendations on how to control one’s pH.  When, in fact, most all include some form of calcium.  No matter if we speak of crushed coral, eggshells, limestone, pulverized lime, or any other source of calcium it is all some form of calcium.  I do understand that different forms will act differently, but yet believe they can all be used each with their own advantages and disadvantages.  And then there is the potassium form of buffer.  Which does one choose?  Each has their proponents and defends their stance avidly.  Perhaps they are all right and there is no BEST answer.  What to do, what to do?

Well, I will tell you what I did.  I bit the bullet and just did something.  Maybe not the brightest move I have ever made, the outcome is yet to be determined.  I already had a 40 lb sack of Barn Lime (calcium carbonate) and  I Googled up “calcium carbonate” in order to determine the correct amount to add.  That did not help much as the formula given was to raise it 1 degree of hardness or dH not pH.   I have total about 350 gals of water including all vessels.  The formula called for 2 tsps to 50 gals of water to raise it 1 degree.   What the heck is a degree anyway?  Well I knew that my pH was so low I couldn’t read it so I took a SEWAG.  350/50=7 and  7*2tsps = 14.  I had already added 8 tsps; a little each day over the past several days and nothing was showing thus far so I thought that 12 tsps would be about right.  And so last night I put 12 tsps in my sump.  Early this morning, I went out to check pH not really expecting a lot of movement and it read 7.8 pH.  Later, about mid-morning I checked it again and it read 6.6.  There is still a lot of lime in the bottom of my sump and fish tank.  I know that lime does not dissolve, but rather it is somehow absorbed into the water.  I also know the finer the consistency of your calcium media the faster the reaction.  This was the consistency of coarse powder or fine sand.   It has awakened my nitrates and they are at 2.5 with .25 ammo and 0 nitrites.  Now, the waiting game begins to see how it all works out.  

Anyone have enough experience with what I did to tell me if I screwed the pooch and happily stumbled into a solution?

Ok, so in my effort to understand what is going on with my water chemistry I found a couple of links to an aquarium products site that has two interesting articles. I just quickly skimmed over them so I can't yet vouch for the contents, and they are geared towards aquarium owners so the products and recommendations discussed do not necessarily fit aquaponics, but the chemistry information and explanation of terms looks interesting and might provide a basis for further discussion on the water chemistry based reasons we are struggling with rapidly dropping pH and lack of stability. When I get time this week I'll read through them in more detail and see if I can figure things out.

 

One article is on calcium, kH, pH, GH, and mineral cations/electrolytes in aquarium systems and how they affect fish health: http://www.americanaquariumproducts.com/AquariumKH.html

The other is on redox potential in aquariums:http://www.americanaquariumproducts.com/Redox_Potential.html

 

I also saw that API has a test kit for GH (general hardness) & KH (carbonate hardness) that might help us better monitor what is going on in our systems.

Casey,

I think you are on point about the hardness test.  I really didn't understand all that I read, it has been awhile since my Chem classes, but I do believe getting an handle on hardness as well as pH would be beneficial.  I am about due to get another master kit and I suppose it would be a good time to get the other to get free shipping on Amazon.  I am reading the first link you posted and it is very informative.  I have read most of this information in other places, but it seems the more I read it, the clearer my understanding.  I think I will save the link to refer back to.


Casey Haas said:

Ok, so in my effort to understand what is going on with my water chemistry I found a couple of links to an aquarium products site that has two interesting articles. I just quickly skimmed over them so I can't yet vouch for the contents, and they are geared towards aquarium owners so the products and recommendations discussed do not necessarily fit aquaponics, but the chemistry information and explanation of terms looks interesting and might provide a basis for further discussion on the water chemistry based reasons we are struggling with rapidly dropping pH and lack of stability. When I get time this week I'll read through them in more detail and see if I can figure things out.

 

One article is on calcium, kH, pH, GH, and mineral cations/electrolytes in aquarium systems and how they affect fish health: http://www.americanaquariumproducts.com/AquariumKH.html

The other is on redox potential in aquariums:http://www.americanaquariumproducts.com/Redox_Potential.html

 

I also saw that API has a test kit for GH (general hardness) & KH (carbonate hardness) that might help us better monitor what is going on in our systems.

Reply to Discussion

RSS

© 2020   Created by Sylvia Bernstein.   Powered by

Badges  |  Report an Issue  |  Terms of Service