Backyard Aquaponics
A place to discuss aquaponics

Soooo,

After many months of reading about aquaponics and building a mini mockup system in a spare bedroom to make sure I can manage the basic plumbing I took the plunge. I bought a modest greenhouse, dug a 300 gallon hole and filled it with water. After running water between the hole and a half barrel ebb n flow bed for a little over a month to identify and correct any issues, I started adding fish. Koi to be exact.

I'm at the point where I need the opinions of more experienced people. I'm using 10 koi fry to supply three grow beds. Two beds are ebb n flow half barrels filled with lava rock for media, and the third bed is a two ft by four ft manufactured deep water trough I found used that holds 15 net pots, 5" diameter each. The grow media is all lava rock and some blown glass that's manufactured as grow media. I'm using a 70 gallon sump tank as the water supply for the grow beds and all grow beds empty into the fish pond. The fish pond overflows back into the sump tank. The grow beds are at various ages. One half barrel has been cycling for roughly two months, the other ebb bed is about 3 weeks old and the trough bed was plumbed in yesterday.

Overall I'm growing roughly 50 plants of various types and sizes. Some are simple herbs like parsley and others are large fruit bearing vines like watermelon. So far the plants are all healthy and many are bearing fruit.

Like many others on the forum, the PH level is fairly high at 8.0 and my water is basically yellowish in color. I also have a bit of algae growth in the pond and sump. Ammonia, nitrite, and nitrate are all at levels essentially zero.

I'm not experiencing any problems that I know of. The fish are active and eat often. They get fed several times a day. The plants might be just a bit yellowish but are also active and rowing well.

Should I be concerned at the apparent lack of nitrates?
Should I consider adding iron yet? Or at all?
Is the algae going to be a problem? Is it correctable?

My goal is to let the koi help me get things established and hopefully survive any mistakes I might make and prepare the water for a more tasty fish like trout once I know the water will support them and I get the permits required by my state.

With these goals in mind, what direction should I take from here?

Thanks for any input.

It's difficult to say because the fish do sound like they are small in relation to the system but many people with established systems run with 0 nitrates and no ill effects because the plants are getting what they need. It's also true that it doesn't take many fish to supply enough Nitrates to run a system.

I would look at getting chelated iron in case you need it (with the high pH you probably will). Look for a type that works at the higher pH that you have. Here is an explanation http://www.youtube.com/watch?v=E4_hCAnymFw
In this case it looks like this would be FeEDDHA and possibly FeDTPA.
Most people also use seaweed extract so it would be a good idea to get this as well. In the states Maxicrop plus Iron (although the iron portion will be locked out for your system because of the pH) is generally used. For people with lower pH's this will also supply the iron. If you can't find what chelated iron you need Maxicrop plus Iron as a foliar spray would probably help since your avoiding the high pH in your system by applying it this way (try to dilute with water having a more neutral pH).

For the algae, if you can, block the light from the fish tank and this will take care of most problems.

Hope this helps

Thanks for the answer Scotty. You're right, my fish are still small. I'm adding them slowly because I'm still concerned about killing them all off. I plan on adding another batch this weekned since the first two batches are still alive and well. Very hungry.

The video link you sent was realy informative. I can't find any of the chelated iron mentioned though. The local hydroponics shops all get hung up on the high PH and are determined that I do something to address it instead of simply adding iron although most aquaponics sites advise against altering the system chemically when the fish and plants seem to be ok. I'll look online for the good stuff in reasonably small quantities. I'm adding some downspouts this weekend as well to divert rainwater into the system. Might as well use it when it's free.

As for the algae, it's been cloudly almost every day for the last couple of weeks (no rain though) and the algae took care of itself. I did cover the sump with some old fence slats to keep it dark. The water is still al ittle yellow.

It's still quite warm here and will be for at least the next few months, but winter will get here and I don't want to fall behind then. What is everybody using to keep their systems warm enough?
Do we heat the water or the greenhouse? My FT is 2/3 underground so I'm confident it won't freeze and my choice of koi is because they're hardy enough to last outdoors here. But, I want to grow through the winter in the greenhouse meaning I need water warm enough to keep roots happy and air warm enough not to frost at night. I'm hoping the thermal mass of the water will take care of the air, so how do we keep the water warm?
I will experience temps approaching 0 deg fahrenheit at night. On the bright side, literally, the sun shines here well over 300 days annually so the greenhouse should warm itself up most days.