Backyard Aquaponics
A place to discuss aquaponics

you are absolutely correct.. actually allowing the solids to build up in your filter media may be the best way to allow denitrification to occur.. it allows the bacteria to buildup slowly and let thing adjust slowly over time. I think this may be thw best way to go about introducting denitrification.

but to add to your point of nutrients concentration.. I too observed that as well.. plant growth are always limited by the limited nutrients.. and you may be lacking alot atm.

Well I'll see what the pH is tonight and add some K and Mg (?). This plant stuff is so much harder than the actual physics of systems Mind you it would help if I had a decent lab

Bumping the K and CA could be good but if I'm also taking the fish off their feed then it won't lower the pH in response to the increase from adding K and Ca

I agreed with thd lab.. I wish I had access to one as well

I'm not sure about that.. best to add a more ph neutral form of calcium and potassium I suggest adding some magnesium as well.. atm I'm expermenting with a 1 part calcium chloride to 1 part potassium sulfate to 0.5 part magnesium sulfate (epsom salt) by weight at all additions.. a dont ever add one by themselves to prevent one over competiting with each other.. you can try it and see if u see a difference.. I surely did

Stuart there is another helpful alternative,Foliar Application.I have been working on this now for nearly a year,mostly because my PH wouldn’t come down to allow using system dosing.
Calcium Chloride is excellent for foliar as is magnesium due to there solubility,Potassium Nitrate or Sulphate for K,you can mix calcium and magnesium together or potassium/magnessium but you can’t add calcium and potassium together due to the calcium precipitating out of solution.
I have a 20litre water drinking water bottle with a tap in the bottom,in this a mix EDDHA 5ml,a dash of Neem oil and another oil based products that has shown itself to help with aphids,plus EM1A,when i want to spray i add to the sprayer Calcium, Potassium or magnesium top up to the mark give it a shake to mix and off we go.
When my system was stuck for months at 7.4 ish i added nothing to the system i just used foliar applications for good results.

Are you still using wood ash cookie?

Couln't find MgCl but I did find MgNO3

They don't have Fe HBED and they were out of stock of CaCl

I'm getting some KSO4 and MgSO4.

Although I've just seen Mono Potassium Phosphate KH2PO4 Any good to give K and P given discussions about P deficiency elsewhere on the forum?

I realise I've been made such a mistake

Remember the second test tube in the last photo was the well water?

Well since the well has nitrates I can't just multiply the measured concentration by the dilution factor can I

I've re measured.

Well water 10ppm
Sample 20ppm

0.9x10+[NO3]x0.1=20

9+[NO3]/10=20
[NO3]/10=11
[NO3]=110ppm

AHAAHAA.... lol nitrates = 110ppm... Stuart you crack me up.. well definitely you have a deficiency problem for sure.. atm I don't use wood ash just simply because I'm tryin to understand this aquaponics thing a bit better I'm using known amounts of components to ensure that its the actual amounts of potassium and calcium im inputing into the system. However if I had a lab I can see exactly whats deficient and suplement occurdingly... but I don't got that privilege. so I hypothesize and decided to supplement these minerals not on to hold a certain ppm.. but base on my fish food usage for the day. I decided firstly to use a factor of 2% of to weigh of my fish feed input per day I'll add as potassium sulfate and calcium chloride respectively.. 1.5% as Epsom salt.. and see how that goes.. so far its going well.. I'll increase dosing in the future to see if it makes a difference.

The nitrate could still have been locking out other nutrients because its now down to 110ppm after three large water changes.

I've added a bit of KHCO3 and I'll add some more CaOH once I've seen the pH response.

oh yea true.. then I was really high then. yea you do that but try to add magnesium as well.. my fish food I used is very low in potassium and magnesium. and hence the reason I have to supplement them.

I'll add some epsom salts as well then.

Cookie, does that mean if you have 100g of feed, you'll add 2g of potassium sulfate, 2 g of CaCl and 1.5 g of epsom salts? Are these % based on desired NPK ratios assuming a certain amount of immediately soluble N from the feed?

Or are they more empirically derived? Funny I had the thought of doing this while driving to work today!

Would plants be using as much Ca as K and half as much Mg? Never looked into it though that would suggest Ca should be considered a macro nutrient also.