New Micro Farm System

[Apollo]

"The nitrates are over 80 ppm and I need to do a dilution test to bring them into a measurable range with the API test kit."

Does this mean that you're going to do water exchange's to get you nitrates below 80 ppm? My test kit goes up to 140 ppm...is water exchanges better for the fish than reducing there food supply?

[Oliver]

Does this mean that you're going to do water exchange's to get you nitrates below 80 ppm? My test kit goes up to 140 ppm...is water exchanges better for the fish than reducing there food supply?

What I was referring to is that the API test kit does not give an accurate nitrate color representation once you get above 40 ppm. In order to place the nitrates in the color range of 40 ppm or below you need to dilute your test water with non-nitrate water and multiply the results by the dilution ratio. As an example, if you dilute the fish tank water in the test tube by a ratio of 4:1 with distilled water (4 parts total, 3 distilled, 1 FT water) then you would multiply the measured results by 4.

Once the nitrates reach a steady state equilibrium between the amount of food you are feeding the fish (that ultimately produces the nitrates) and the amount of nitrate uptake by the plants, reducing the fish food supply we eventually reduce the amount of nitrates in the water, assuming there are no other changes, like a change in the number of plants or their size. So, adjusting the amount of fish food over a given period of time is a good way to regulate your nitrate levels in your aquaponics system, if you have enough fish. Fish have a very wide feeding range.

This places the primary role of the fish as a nitrate producer rather than a food supply for humans. By changing water instead of adjusting the feeding rate and keeping it at maximum grow-out daily amount, you are giving the fish a primary role as a food supply to be later harvested. They can be both, but they have only one primary role; which can change over time like while cycling your system.

Adjusting the fish food supply is a good way to control your water chemistry while your plants are maturing, and even after. Doing a water exchange will also accomplish the same thing but that may not be a good or healthy environmental option. You can always dump some of the water onto an outdoor garden or other non-aquaponic plants to help with the use of the discarded water, but only if your nitrates are too high.

Oliver

[Apollo]

"You can always dump some of the water onto an outdoor garden or other non-aquaponic plants to help with the use of the discarded water, but only if your nitrates are too high"

So what is considered too high?

[Oliver]

"You can always dump some of the water onto an outdoor garden or other non-aquaponic plants to help with the use of the discarded water, but only if your nitrates are too high"

So what is considered too high?

Good question. It really depends on the fish you are raising. With Tilapia, my guess is that if you stay below 100 ppm then you are probably safe. As you push up above 150 ppm we have found that you start to kill fish. Again, we really don't know what that high number is due to the inaccuracy of the test kit. That is why we started doing the dilution test in order to get a more accurate Nitrate measurement when we have a high Nitrate count.

Oliver

[davidstcldfl]

Wow Oliver, what a nice set up... Very clean and professional looking!

On the horz ducts....what is the depth of water in them..?...and the flow rate through them..?
On the vert ducts, I noticed you removed what appears to be a plug/clean out. Is this where the water drains from the vert ducts..?

Once again, 'very impressive’
Thanks for sharing the tip on nitrate testing..

[Oliver]

On the horz ducts....what is the depth of water in them..?...and the flow rate through them..?
On the vert ducts, I noticed you removed what appears to be a plug/clean out. Is this where the water drains from the vert ducts..?

David, thank you for the compliments.

The horizontal ducts are 5 inches square on the outside, a little less on the inside. There is a 3 inch high (adjustable) riser on the drain end connected to a bulkhead on the bottom of the duct. The bulkhead has an outside protrusion designed as a barbed fitting. That protrusion sits in a hole in a 4 inch drain-back pipe that runs along the edge of the table just below the end of the ducts. This helps position the ducts on the drain end. The water enters on the opposite end of the duct through another bulkhead fitting on the bottom as well, with no riser inside. In future designs the input to the ducts will be through Uniseals.

We have yet to measure the flow rates on the horizontal ducts but plan to do so soon. The water feeding the manifold for the whole horizontal system is adjustable. Each vertical two back-to-back arrays has a single manifold up high and water flow adjustment to it. The flow in both horizontal and vertical ducts, to the individual duct, is balanced out by the ratio of the size of the feeder tube to the size of the feeder manifold. The duct feeder tubes offer some resistance to flow thereby balancing out the flow to each duct.

The drains on the vertical are the same bulkhead fitting as the horizontal, except they are located on the end cap with no internal riser. They also sit in holes in the drain pipe for location. The horizontal ducts are DWC and the vertical ducts are NFT. The service caps on the vertical ducts are missing because the hole is slightly too small for the caps and needs to be enlarged in order for them to fit properly. It has given us an opportunity to observe the water flow and root growth as well as any root interference with the vertical duct drain, which hasn't been a problem.

Oliver

[Apollo]

Oliver, thanks for the new information on Nitrate's...how high is too high. It answered one of my most asked questions and is the best answer as to why my fish were dying.

Your statement on trying to determine where the level was once it exceeded 40 ppm was right on...mine were pushing 200 ppm. I did it your way "if you dilute the fish tank water in the test tube by a ratio of 4:1 with distilled water (4 parts total, 3 distilled, 1 FT water) then you would multiply the measured results by 4." to find out what my Nitrate level was at.

Now let me ask you this, I just took my FT water and add 2 drop instead of 10 drops to test the water. That's 20% testing solution into the FT water, than multiplied the reading by 5 to bring it back up to the 100% range. It seems to me that the read out is the same...which was way too high. I backed off on fish food and started doing water exchanges to get my Nitrate level back down to around 100 ppm.

I also think that the high Nitrate level had a negative affect on my plants.

[Oliver]

Now let me ask you this, I just took my FT water and add 2 drop instead of 10 drops to test the water. That's 20% testing solution into the FT water, than multiplied the reading by 5 to bring it back up to the 100% range. It seems to me that the read out is the same...

That might work. You can do it both ways and see if you get the same results.

My guess is that for the color to be right you would need to use the full count on the drops.

Let us know your results.

Oliver

[Aloha Don]

Great thread Oliver.
Thanks for sharing
Any updates that we can learn from?

[topz]

Oliver how is the system doing haven't seen any new posts in almost a year