Maxi-Crop in Mixed Media System

[Josh]

Hey.  I have a question about mineral deficiency and my mixed media system.  I see signs of iron deficiency in my raft bed, ( yellowing leaves with green veins).  I bought some maxicrop with iron but IM not sure where to add it or how much to add.  

 

The system is still not completely cycled, so I know that the nutrients have not built up yet,  but there are nitrates present and the plants in the gravel bed look great.  The system has a FT of about 400 gallons but only 20 or so medium to large wild caught tilapia, a gravel bed of roughly 180 gallons of river rock and a raft bed that holds about 120 gallons.

 

Being that it is a mixed media system, I'm not sure how to proceed.  I bought a quart of the stuff.

 

Any thoughts are really appreciated.  Thanks

 

Josh

[Averan]

similar situation here, although i'm sure my system is fully cycled and mature.  i hate adding seaweed fertilizers as it feels like cheating!  i mean, why bother building an aquaponics system if i'm just going to use a powdered fertilizer anyways?

[TCLynx]

Well fish foods and source water does not always contain everything needed.  Potassium is commonly supplemented as is Iron depending on your pH and source water.

 

When supplementing with Maxicrop I usually recommend reading the bottle.  I will probably have a recommendation for an amount to add to some amount of water and then spray over some square footage of growing area.  It is not the amount of water you are interested in but the amount of growing area.  So say they recommend using like 1 oz of extract mixed in water and used to feed say 100 square feet.  If you have 100 square feet of growing area, then add that 1 oz to your water.  Now these numbers are only an example please read the bottle I don't have one in front of me and I don't remember the exact dosage.  Now if you are seeing the deficiency in the raft bed the I would add the extract to the raft bed.  It will mix all over the system and turn your water tea colored but the fish generally don't mind that.

 

Now many people have found that they need to supplement more heavily during the first season and then in later seasons have found they don't need to supplement at all.  The quality of your fish food will greatly affect how much you may need to supplement as will your source water.  If you are feeding cheap pond diet or goldfish flakes, you may find you have more nutrient deficiencies in your plants than if you feed a high quality dense culture feed for recirculating aquaculture.  See the pond diet sorts of feed are designed to just get a little extra growth from fish that are otherwise mostly eating a natural diet from the pond and therefore are not really complete feeds.  The Goldfish flakes or other aquarium or ornamental feeds are designed to keep the fish alive while providing the least nutrition possible so that aquarium and pond keepers can get away with the least amount of water changes possible which is kinda counter productive for aquaponics.

 

I don't recommend adding supplements all the time, only when you plants show they need it.

[Josh]

Thanks for the info.  I added a bit less than a cap full.  Seemed appropriate.  Hopefully, this is the last time I'll have to use it!

 

 

[TCLynx]

Or you might add a cap full every few weeks if you see signs that the plants seem to want it.

[Josh]

I'll try to let the plant tell me what they need.  Thanks for the help!

[Nate Storey]

I don't do maxi-crop- just use straight up chelated iron.  $40 in chelated iron has lasted me two years and will probably last me another 10-12 more for two 2000 gallon systems.  it saves money in the long run.  TC is right- you should switch over to a commercial feed of some type to get all of your micronutrients, and then use KOH for some of your pH raising in addition to hydrated lime.

[Sylvia Bernstein]

Joshua, iron is highly sensitive to pH as well.  What is the pH of your system?

[Josh]

Hi Sylvia,

My ph runs a bit high, around 7.6, although my nitrogen cycle is not yet complete.  I hope it will fall once the cycle is finished.  I am aware of iron lock out due to high ph.  I am happy to report, however, that I am seeing some signs of improvement after dosing the maxi-crop, (general "green-ing" of leaves).

 

Thanks.

[Nate Storey]

i don't know if maxi-crop contains chelated iron or what percentage, but a pinch of chelated iron would help green up your stuff.  that's the point of chelation- it attaches an amino group to your iron so it's plant-available even at high pHs.

[Josh]

Thanks.  The maxi crop i have has iron at a 2% concentration.  Given the high ph, tho, maybe chelated is the way to go.

[Stephen Eugene Robinson]

I am using Purina Catfish food to feed my Tilapia.  Does anyone have experience with this feed?  Is there anothe that would be better for he plants?

 
TCLynx said:

Well fish foods and source water does not always contain everything needed.  Potassium is commonly supplemented as is Iron depending on your pH and source water.

 

When supplementing with Maxicrop I usually recommend reading the bottle.  I will probably have a recommendation for an amount to add to some amount of water and then spray over some square footage of growing area.  It is not the amount of water you are interested in but the amount of growing area.  So say they recommend using like 1 oz of extract mixed in water and used to feed say 100 square feet.  If you have 100 square feet of growing area, then add that 1 oz to your water.  Now these numbers are only an example please read the bottle I don't have one in front of me and I don't remember the exact dosage.  Now if you are seeing the deficiency in the raft bed the I would add the extract to the raft bed.  It will mix all over the system and turn your water tea colored but the fish generally don't mind that.

 

Now many people have found that they need to supplement more heavily during the first season and then in later seasons have found they don't need to supplement at all.  The quality of your fish food will greatly affect how much you may need to supplement as will your source water.  If you are feeding cheap pond diet or goldfish flakes, you may find you have more nutrient deficiencies in your plants than if you feed a high quality dense culture feed for recirculating aquaculture.  See the pond diet sorts of feed are designed to just get a little extra growth from fish that are otherwise mostly eating a natural diet from the pond and therefore are not really complete feeds.  The Goldfish flakes or other aquarium or ornamental feeds are designed to keep the fish alive while providing the least nutrition possible so that aquarium and pond keepers can get away with the least amount of water changes possible which is kinda counter productive for aquaponics.

 

I don't recommend adding supplements all the time, only when you plants show they need it.

[TCLynx]

I use Aquamax 4000, it seemed to work well for the tilapia and my catfish and my bluegill.  It is a dense culture feed designed for recirculating aquaculture systems.  It is a purina product so your feed store (well not tractor supply) if they are a purina dealer should be able to get it for you if you ask.  You don't want them to carry it all the time (since fish feed goes bad if sitting on the shelf for months), you want to find out what their ordering schedule with purina is like.  So if they put in their orders on Monday Morning, you want to call them before then so they can have a bag added to the next order for you and find out when the delivery truck usually comes in so you don't drive over before it has arrived.