Fertilization Strategies

Hi Prof Dirk

How are the tanks coming along with the new NPK mix? Any updates? I know you said you are quite busy right now, but I'd be very interested in your latest findings. You did mention you had some GSA on your high light tanks. Any news fixing that problem? Was it only GSA or any other algae too?

Regards
Lauré

 

I have an interesting situation which I have been able to replicate exactly for the last 3 weeks running.
Day 1 - 50% WC
Day 3 - tiny bit of cyanobacteria (BGA)
Day 6 - tiny bit of GSA
Day 7 - more GSA

BGA caused by low NO3; GSA caused by high NO3. This is, of course, in relation to PO4.

I haven't been testing NO3 as I have found 3 different test kits with 3 vastly different results and so I have now abandoned testing for NO3 as it can't be trusted. I know the algae does not lie - so early in the week after WC I have almost 0ppm NO3 and that is why I get BGA. But NO3 builds up quite quickly and then of course BGA growth is suppressed and it can't bloom. That is why it remains just a tiny bit.

The next thing that follows is GSA, as a result of the NO3 building up so quickly towards the end of the week.

And currently I do not dose any nitrogen other that what is produced by my biofilter.

Now what is happening here? Any thoughts? Are my plants not using NO3 quickly enough towards the end of the week? Or is the NO3 uptake very high after WC? Perhaps due to additional CO2 in the water after WC?

Regards
Lauré

 

I'd be keen to see the results if you half your feeding quantities but do the rest the same.

 

kan ek vir jul n vraag vra wat ek oor wonder
maak dit saak van waar die lig kom wat ek bedoen moet jy ligte altyd bo jou tenk sit

 

wil probably be confusing for fish if your light source comes from the side?

 

maar 2 ligte van die kant en se 2 ligte van bo ligte van kant sal nader aan plante wees en so meer krag he

 

Hi Laure,

I find it interesting (after reading the PM regarding what is what here), that you go from low NO3 to high NO3 within a 2 to 3 days. I would assume your tank is fairly heavily planted? And I doubt you have overstocked the tank... because then you wouldn't get BGS.

It's such a pity that one can't get an accurate and reliable reading of NO3... because it would be interesting to see the rate of growth... it would appear... and I've seen it in my tank, that NO3 seems to grow exponentially. I mean, one day is a few spots of GSA, and the next that spot have grown considerably. It would APPEAR to me that the plants are not using all the NO3 then? But then how do people like Solex get away with hardly EVER doing water changes, and NEVER get any algae?

ANother thing to consider... WC results in us picking up a lot of debris and waste off the floor. During the week, this debris builds up... could it not be that on day 3-6 that this debris has been broken down enough in the water to warrant the NO3 build up?

I did a good glass scrub and WC last night. It will be interesting to see when my GSA appears. Granted my CO2 input is not calculated or monitored... but this is definately interesting.

 

Who says that Solex NEVER get's algae? I have seen algae problems in his tanks - not sure whether it is now sorted out though....

 

Sorry... let me rephrase that... Solex hardly every get's algae... my booboo

 

hahaha - no probs Zoom, although he does have algae issues as well, just not GSA that I know of.

 

It could very well be the extra CO2 in the water after the water change.I inject a fair amount of CO2 at the moment and add KNO3 in the EI method.With the first dose on day one after WC there is no BBA,on day 3 GSA appears and a little BBA,on day 4 GSA stops growing and BBA increases,on day 6 plant growth has increased to the point that water flow in the tank has been restricted and BBA has exploded.Nitrate bottoms out.
So with the increased CO2 and extra nitrogen,the excelent plant growth is causing more problems.
Next step is to increased flow or filtration.
What do you think?
Regards
Rudi

 

Rudi, when you say BBA do you mean Black Brush Algae, also known as Black Beard Algae? BBA generally refers to a number of red algae types (Rhodopyta sp.) of which none is actually red!

BBA in almost all cases caused by low or fluctuating CO2 in relation to fertilizers and light. Perhaps your CO2 is too low?

It seems your nitrates go down over the course of the week, due to plants consuming more than you add. How frequently do you dose KNO3? You need a steady supply over the week.

 

Prof Dirk

I notice you have been a little quiet here lately. I am assuming heavy workload at the University.

When you get some time I could you perhaps comment on the issue of adding Fe and the reaction with PO4 to form iron phosphate which is then obviously no longer available to the plants? Or is this not an issue if the concentrations are not very high, as for example in a tank? I would just like to understand that process and how your fertilizer mix is designed to combat this. You don't have to give away any secrets, I just need a bit of clarity on the issue! :smile1:

Regards
Lauré

 

Hi Lauré,

Just a quick reply because I am inundated with work as you correctly indicate.

My plant feeding mix part of the Dirk's drops fertilizer contains the iron that plants need. It contains no phosphate as a matter of fact my present fertilizer mix contains no phosphate. The iron concentration of my fertilizer is low, because only low levels are required. The phosphate levels in aquaria, even if you add some according to the EI formula are low. As a result the formation of iron phosphate is not an issue because both components occur at such low concentrations.

I will hopefully be able to reply next week again to all the questions asked on this thread.

Kind regards,

Dirk

 

HI Laure
Firstly,thanks for the reply.:smile1:
Second,I'm sorry,made a big mistake.I didn't read through the reply before posting it.I meant BGA,cyanobacteria,not BBA.Got my B's and G's mixed up.
At the moment I dose 30ppm KNO3 per week.I split it up into 3 doses,so it's 10ppm every second day.I've also left out PO4 for this week just to see how it goes.
I made a big trim on Sunday and repositiond the filter outlet to create better circulation.I'll wait out the week and see what the effect is on the plant growth.

 

Firstly, let me post a small correction. BBA in freshwater is hardly ever red. In Marine tanks it can be red. Moving on.

I'm not sure if this should be posted here or in my tank journal thread (http://www.tropicalaquarium.co.za/showthread.php?t=1300), but I believe the discussion is probably more relevant to this topic. I will cross-link this post in my tank journal thread.

On Friday I did an 80% WC. I was getting a bit fed up with the Green Dust Algae on the glass. I also know that you can wipe it down, but some of the spores get into the water and reattach an hour or two later and the next day you are back where you started. So I took out as much water as possible, then wiped the exposed glass down with paper towels. I then cleaned the submerged section of the glass with a sponge, filled up, waited 1 hour and emptied again down to as low a level as possible. The plan was to get rid of as much of the spores stills swimming around in the water. Of course I filled it again afterwards.

I had in my cupboard a solution of KNO3 and distilled water, carefully measured so that 10ml added to my tank will increase NO3 by 5ppm. I thought I'd add 5ml every day and see what happens.

There is good news and bad news. The good news is that I have no GDA whatsoever at this point. I also have no Green Spot Algae (GSA) yet. I will continue to dose KNO3 daily until I have GSA. I will then know exactly what my tank's consumption is, having basically done a major "reset".

The bad news is that yesterday I discovered Blue Green Algae - yep I thought I got rid of it - but I am pretty sure the large WC caused nitrates to be so low in relation to PO4 and light that BGA took the gap. I don't have a major outbreak, because I have been dosing KNO3 at 2.5ppm every day. But I have some and I want to terminate them! I also recently did quite a trim, so I don't think my plants need a hell of a lot of nitrate. Perhaps I was wrong...

I considered 3-day blackout, but in the end decided on medication. I had ordered from Prof Dirk the anti-BGA stuff he sells and I thought now is the time to see if this really works. It is apparently a 4-week course. We will see.

In the meantime, I will manually remove what I can with my hands and then vacuum them up. This is quite easy, actually.

Furthermore, I am increasing my surface aggitation a little by angling the spray bars a little more towards the surface. Hopefully I can increase O2 as I have a theory BGA does not like high levels of O2 in the water.

My latest Tetra NO3 test indicates 15ppm. I still don't know if I can trust this reading. Now it could be my PO4 is high and the balance between NO3 and PO4 is out and this is why I now have BGA. So this is a bit of a catch 22. Do I try to increase NO3 or decrease PO4? The former is much simpler.

Regards
Lauré

 

Laure, just out of interests sake, how often do you do water changes and how much do you change?

 

lol, reading all your posts gives me this mental impression of *Laure the mad scientist*

but still, very interesting and informative reads, i must say

 

Mad for sure; scientist...nope

Weekly 30% is normal for me

 

It is a long read, but quite interesting. Touches on many of the topics we discuss here.

http://www.barrreport.com/estimative-index/6166-methods-algae-control-growing-plants-2.html