Black leaf edges - cause?

[TrevC]

So - several weeks on and an update plus pics. I've done some pruning of the large stems at the back (Alternanthera Reineckii and Lymnophila Aromatica). Interestingly some of the latter had black edged leaves only in the mid-height portion - with very old leaves and newer ones not much affected. I assume this suggests that at some stage (when I first changed my light?), the plants suffered a deficiency of an immobile nutrient which is now being exploited by diatoms (or maybe i am talking rubbish!).

My main concern relates to the S Repens and Monte Carlo in the foreground (with lightly browned sand around them and through the front glass). The Monte Carlo is patchy - reason not clear but i understand this can be a thing in the short term. The S Repens however seems destined to all wither and die looking very sad. Interestingly there are a few stems of L Aromatica to the left of the S Repens (pic) and this initially did very well and now seems to be deteriorating in the last 2-3 weeks. On the other side of the same rock the L Aromatica is relatively fine (left of main pic)!!

Dosing with APT Complete 3 continues. CO2 fine/stable and flow good. It did occur to me that my newbee brain may have overlooked substrate fertilisation. When I first set up the tank 7 months ago, i used Kugeln clay balls. I have now put some TNC plugs under the replanted rear stems and under the foreground S Repens (some might be save-able?) and the Monte Carlo.... plus some Tetra Initial Sticks.

I will see what happens here for the next few weeks (i might learn something) but if the S Repens continues to wither I'll cut my losses here and plant something different (ideas?).

As always, comments/suggestions welcome.

 

[dw1305]

Hi all,

Interestingly some of the latter had black edged leaves only in the mid-height portion - with very old leaves and newer ones not much affected. I assume this suggests that at some stage (when I first changed my light?), the plants suffered a deficiency of an immobile nutrient which is now being exploited by diatoms (or maybe i am talking rubbish!).

I think that is <"probably right">, not rubbish. It would be like @Lapul 's Bacopa <"Should i start to fertilize?">, but presumably with a different element deficient.

cheers Darrel

 

[Tomfish]

I know this has already been alluded to, but I suspect inadequate flow is the main problem. Whilst the 10x rule is only guide, the filter the OP is using over 2x under this. Poor flow can create problems with the distribution of co2, but also distribution of other nutrients, so this problem could account for apparent nutrient deficiencies too. It is also telling that you are having the biggest problems with the monte Carlo and s repens as they sit lower in the tank. Unfortunately my experience (lots of ups and downs since 2011!) has led me to appreciate how fickled flow can be. Many moons ago when I could be arsed with a larger planted tank if found combining pumps and spray bars a difficult mix. Good flow depends largely on a consistent circular motion of water around the whole tank, spray bars from the back down the front of the glass and to the back and up, and lily pipes, pumps etc circling horizontally around the walls of the tank. I think a spraybar would be more difficult to work in your situation, at least with out getting another filter and spray bar, and your tank is quite deep. Perhaps the easiest solution would be use a more standard filter outlet across the front and your pump in the opposite corner pushing the circular flow the other way along the back. Good luck

 

[TrevC]

Hi @Tomfish - I planted the MC and S Repens in May/June but did not address the flow side (following input from this forum) until only recently (late July onwards) when they were already suffering. I have attached a pic with the configuration indicated. The spray bar ( 75% the length of the tank) sends CO2 across from the back and down the front (evidenced by mist and CO2 checker). The powerhead far right (2000 l/hr) is angled right to left and down as per indicated arrow. The stems far left are all nicely waving 🙂 My new APS SKIM-1 (back left) directs flow across the back of the tank (I have it about 50% of its 300 l/hr). Outflow to filter is back right. All in all i'm sort of getting a circular flow. The powerhead and skimmer are on the same timer running 8am-3pm (during all but the last few hours of the CO2 injection time) then again from 9pm to midnight. Ferts are added normally 8-9am daily. Observations welcome.

 

[Tomfish]

I can definitely see the merits of waiting to see if the present flow works, as you never know what's working with constant changes, but my point is that the 'sort of' circular flow you describe may not have the desired effect.
In particular that pump is powerful and will move a lot of water, as such I think it may have a disruptive effect on the more 'delicate' flow from the spray bar.
However if you changed stuff with every online suggestion your tank and wallet would not be in a good place😄 but if your still having problems after trying other things you might consider a more simplified flow pattern. Cheers

 

[Tomfish]

Also having the powerhead turn off before the end of the photoperiod is probably not a good idea, as consistency across the photoperiod is best

 

[kkman]

Any updates ? Did you win the fight ?

 

[TrevC]

So ... much has been tried and I have not conquered the issue really. Some updated pics are attached which show the black edges in the front on Dwarf Sag (front) and Hydrophila Aromatica (front left and at the back but difficult to see) .

Key points:

1. I wanted to eliminate nutrient deficiency as a cause so in early Nov, I switched from APT 3 Complete to EI dosing using APT-e.
2. I also have some persistent GSA and decided to add additional Phosphorous via a solution of KH2PO4. By my calcs, APT-e provided 0.2ppm P and I looked to double this. Have tried this for a month but no major change.
3. As far as the substrate nutrients are concerned, all but the front has Fluval Stratum in mesh bags capped with sand (tank is 1yr old). Nothing much other than sand in the front 6 inches although I have used TNC root tabs and Tetra Initial Sticks here to support various 'carpeting' plant attempts - S Repens (black edges), Monte Carlo and Marsilea Minuta didn't do well which is why I tried the Dwarf Sag.
4. On the flow side, I still have the spray bar, intermittent powerhead and intermittent skimmer going (both about 30% of the time in 15min bursts)
5. In the last few months I have added Bacopa (back left), Rotala Rotundifolio (left) and Rotala Orange Juice (centre) plus a view bunches of Hydrocotyle Partita a month ago (one left front to see how it does vs that attached to wood).

My light is a Fluval Plant 3.0 46W 6500k 3300lum on 100% except blue 15% and Red 85% on 7hrs a day.

As the tank is quite deep I am coming more round to the idea that the low plants which suffer from the black edges (particularly at the front like the dwarf sag) may not have enough light. When I'm back from vacation in about a month I was going to try phically lowering the light and removing the glass evaporation covers - but worried it might accelerate the GSA.

As always, thoughts/ideas welcome.

(As an aside, the Crytocoryne undulatus Kasselman on the right is making a takeover bid to carpet the front right of the tank so at least that is really happy!)

Trevor

 

[G H Nelson]

Hi @Trevor C
Purchase a selection of floating plants Amazon Frobit/Pistia stratiotes/Red Root Floaters!
These three can guide you to what could be happening in the water column regarding nutrients levels.
The plants look pale to me.....the middle image above.
There is one stem of Rotala where you have made changes for the good....you can see it in its growth pattern
But this could also be a lighting response?
The Anubias looks Iron deficient also.
Take a few tops off the Limnophila aromatica leave them floating for a few weeks.
Observe the colour of the leaves, pale green add Nitrate and a Iron supplement that's suitable for your tap water parameters.
Cheers
hoggie

 

[Hufsa]

Apologies for the brief reply here, I think the tank looks better overall, but I still see chlorosis.
I think this tank is a really good candidate for spiking with some extra chelated Iron and Manganese.
I suspect whatever chelates are being used in the premixed fertilizers are not quite cutting it.
Solufeed do sell the powders, but unless OP really wants to buy two kilos worth of trace elements that will last for generations, I would suggest asking on the sales forum if someone will sell you a portion of their stash.
You would want Fe DTPA, Mn EDTA and possibly a little bit of Fe EDDHA.
If you get the powders you can post here and we will help you with the math (send me a message to remind me if im not around to see the post)

The persistence of the diatom algae is fascinating, although im sure the OP does not share my view 😅
I have a small relatively heretical theory about it, but until the plant growth is completely fixed we wont know if the diatoms are thriving independently of the plant issues or not.

 

[TrevC]

Hi @Hufsa I can get the FE DTPA and Mn EDTA here in the UK from Aqua Plants Care in 50g batches at a reasonable cost (although the Fe is currently out of stock). After my upcoming vacation I had intended to make my own ferts instead of the pre-mix so will ping you mid-March when i'm back and have the salts.

On a related subject re: the Fe, I have largely held off from using the filter's UV lamp (esp in the few hours after dosing) as I understand this can compromise the Fe effectiveness.

rgds
Trevor