Aquaponic Gardening

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2 month system. Plants good, not great, fish dying off

Hello, I've been a reader of posts here, but this is my first time being of a poster of posts.

I've got a small 100 gallon flood and drain setup that's pretty young at just about 2 months. I've got lots of stuff growing really well (tomatoes, lettuce, peas, chard, herbs, and flowers.

I did a fishless cycle and my levels are all pretty good except my pH is high at about 8.2. I've been adding about 1/4C of lemon juice to the system a couple times a week to knock that down, it works for a day or so, but the pH creeps right back up every time.

Now my plants are starting to show signs of yellowing on the edges of leaves. This is happening with my tomatoes and my peas primarily. I'm also seeing a pretty regular die off my goldfish. I added about 25 small (2"-3") fish about 3 weeks ago. They seemed quite happy at the time, eating well, playing in the surface of the water when the grow beds would drain back into their tank. However, now the fish that are left aren't eating much and are pretty lethargic.

My biggest concern is my water quality. I'm on a well that has extremely hard water. I use potassium as a softener, not salt, so I used this water to start my system. Well, after my pH went up so high I did a 80% water change using collected rain water and melted snow to replace it thinking this might help. Apparently it hasn't done a whole lot of good. Any thoughts from the community members would be helpful as I'm not sure what to do at this time. Thanks for your input!

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I thought I should add a little more detail about my situation.

My levels are as follows:

pH 8.2 (I knock it down with lemon juice to about 6.8, but it goes back up in 24 hours)

Ammonia 0-.25

Nitrite 0-.25

Nitrate 40

Water Temp 69

Indoor converted room to greenhouse, holds at about 65-70 degrees F in there. Hydroton as media. Thanks!

Lemon juice directly into the system might not be the best choice of acids to use.  Citric acid has antibacterial properties.

You should probably do your pH adjustment to a barrel of water before using that water in your system.  Adding the acid to your system directly as you are seeing is causing pH bouncing which is hard on fish, bacteria, and plants.

So, you will need to figure out how much acid to add to your given amount or prepped top up water.  Do do this by adding a measured amount of say muratic acid (hydrochloric acid) to the barrel of top up water, let it bubble for a day and check the pH again, you will have to keep adding a measured amount of acid daily and check the pH.  Once the pH stays down at the desired level for 24 hours after you add it, then you will count up all the acid it took to counteract the carbonates in your top up water so that in the future, you can use close to that total amount of acid to prep you total amount of top up water.  It is best to do this outside of the system before you add it.

 Just so you know,citric acid is antibacterial and lemon juice being high in that acid means that maybe you have set back your cycling.

Thanks TCLynx. I was just reading another thread you assisted on and I came to a similar conclusion in regards to the lemon juice addition. No more lemon juice directly into my system. Bad AP gardener! I'll see if I can get one of the other acids at my local gardening supply place. I've got several 5 gallon buckets I keep filled with rain water in the indoor garden for top off. I'll test that water now, then add some acid, bubble and let it sit to see what the levels are that I might need. Thanks for your help!

I just realized that Wes, I feel pretty bad about this too. My poor little goldfish are suffering at my hands. No wonder they scatter when I walk into the garden. I will making lemonade from my lemon juice from now on. No more AP-ade.

wes said:

 Just so you know,citric acid is antibacterial and lemon juice being high in that acid means that maybe you have set back your cycling.

Yes indeed, just the ph swings alone can play havoc on your goldfish also.

I thought I was cycled and added 60 catfish and 200 bluegill - promptly killed 58 of the catfish.  The other two are doing great, growing rapidly 4 months later.  I was so confident too that I would not kill off a bunch of fish as so many people do.  They're happy now.  Water is always about neutral, ammonia .25, nitrite always 0 and very little nitrate.  I'd like to see nitrate go up and it probably will once the fish are bigger and eating more.  Good luck.

Jeremy Wheaton said:

My poor little goldfish are suffering at my hands.

So I've got my levels daled in by making small adjustments (5ml at a time) and ph is hovering around 6.8-7.2 now and best of all... No more dead fish! Thanks for the suggestions guys!

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