Plant Uptake

[shane]

I have been trying to figure out what my plant uptake is. I have been testing NO3, PO4, and FE before and after the lights come on/off. I am using Hach and Lamotte test kits with new reagents. Still haven't created any reference solutions as I need to get a accurate scale.

It seems my NO3 is stuck at 18ppm, my PO4 is about 3-3.5ppm, and my FE is at 0.1ppm both before and after the lights turn on/off. These levels have been here for over a week.

I use ADA aquasoil and have discus in a 60 gallon tank. I know the discus are adding NO3. I have been dosing 3 times a week using the following and doing (2) 50% water changes per week:

K2SO4 - 1/4sp
KNO3 - 1/4tsp
KH2PO4 - 1/8tsp
TMG - 4ml daily

Is all the PO4 & NO3 coming from the discus? Thus, the reason the PO4/NO3 levels are not changing?

 

[aaronnorth]

It might be that you have these elements in your tap water, try testing it

thanks

 

[shane]

There is no PO4 or NO3 in the tap water.

 

[Tom Barr]

How many discus and how much food is being feed?

Regards,
Tom Barr

 

[shane]

I have (4) 5"-7" Adult discus. I feed them the 3.5oz Hikari frozen bloodworms via (2) plastic worm feeders. I feed (2) 3.5oz cubes three times a day - so (6) 3.5oz cubes per day. I don't thaw out the blood worms before putting them into the worm feeders. I simply drop the frozen cube into the worm feeder.

 

[Tom Barr]

Well, that's a fair amount.
Generally folks with discus do two things wrong: not enough CO2 and also they reduce the current, which reduces the exchange of O2(low O2) and excess build up of CO2. Larger fish respond first to CO2 issues also.

So that can reduce the amount of NO3 uptake also.
But there's a fair amount of N from the waste it seems like and the ADa As adds some as well.

The plant biomass can alos greatly influence uptake as well. if you have high biomas,s then expect more, less- less uptake and so on.

Your feeding and the dosing for this sized tank and the water changes etc suggest what'd I'd expect though.

18ppm is about right.

Regards,
Tom Barr

 

[shane]

Hi Tom,

I have been trying to dial in how much surface agitation is enough for this tank. I currently use a maxijet 400 powerhead near the surface to agitate the water. Not sure if that is enough or not? I also tried a maxijet 900 but it seemed a bit much to me.

I also have an Eheim 2217 (biological filter) and a Eheim 2028 (mixed mechanical/biological) for filtration. I use an eheim spray bar near the surface pointed downwards to get flow to the front part of the tank. Then I use a Cal Aqua labs output lilly pipe for the rear of the tank.

According to my drop checker with 4KH solution, my CO2 is about 30ppm. I push the CO2 a little more to give it a little extra. My DC is showing a very slight yellow to it.

I have some narrow leaf ferns that used to pearl but no longer are. It seems my limited pearling from the ferns and fast growing plants doesn't happen everyday, only some days. That is why I suspect that something is wrong.

I also have some BBA on slower growing plants (anubius, taiwan moss) and driftwood. The faster growing rotala colorata, rotala rotundifolia, and diandra didipilis is algae-free. I think the BBA came about after a rescape, addition of some new ADA AS, and switch over from ADA ferts to dry ferts. It is hard to say if the core of the BBA problem is fixed or not. I am still getting rid of BBA that has been in the tank from 6 weeks ago plus I have done some changes to combat this and not enough time has passed to quatify if the problem is fixed or not.

I have reduced my light on time to 8 hours/day. I run 150 watts PC lighting. The 95 watt tube is on 8 hours/day and the 55 watt tube is on 4 hours/day.

I used to do (1) 50% water change per week; now I do (2) 50% water changes/week.

My dosing regimine is still up in the air if it is in balance or not. That is why I wanted to see what the plant uptake was.

With regards to PO4 uptake, I am assuming the ADA AS will supply some PO4? As well as any uneaten food (if there is any)? What about fish waste? Any contribution there?

 

[aaronnorth]

well the BBA will probobaly be from the NH3 spike that the AS will give off. Fish waste will release a small amount of PO4.