Getting Pogostemon helferi to grow?

[Whitebeam]

I've tried P. helferi before and it just sat there and slowly died away. That was before I changed from the internal filter to my new shiny Eheim and changed to a single photo period, but the sad remains that are still in the tank refuse to perk up. I've now ordered a new pot and I so much want to be able to get this plant to grow, as I love the look of it. Please would you look at my setup below and see if there's anything I'm missing that this plant wants to be happy?

Peter

Tank: Juwel Rekord 800.
Volume: Water volume above substrate = 79cm(l) x 33.5cm(w) x 34cm(h) = 90l = 23.8USG.
Lighting: 2 x Juwel 18W T8 tubes 55cm usable length (1 x Warm Lite and 1 x Day Lite) 37 cm to substrate. Juwel reflectors on both tubes.
Photo period: 7 hours per day (14:00-21:00).
Filter: Eheim Pro3 350 (model 2073).
Substrate: ~3mm diameter smooth gravel.
CO2: D&D pressurised at about 4 bps to maintain green-yellow in drop checker loaded with homemade 4dKH. Drop checker in vicinity of subject Pogostemon. CO2 on at 12:00, off at 20:00. CO2 introduced into filter return line using Up-Aqua diffuser. Misting.
Ferts: High nitrate tap water (to about 25ppm) and high fish load, so dosing dry ferts at 0.15g KH2PO4 and 1.0g K2SO4 Sun, Tue, & Thu; 3ml TPN and 2ml Flourish Iron Mon, Wed & Fri. AE Aqua Carbon at 9ml after water change, then 2.5ml daily. Weekly dose: K=17ppm, PO4 = 3.5ppm, Fe = 0.75ppm.
Water change: Weekly 50% water change on a Sunday with light vacuuming of visible gravel. Water stats at the end of the week always 25ppm < Nitrate < 50ppm. 0ppm Nitrite. 0ppm Ammonia. GH 220ppm (12dGH). KH 180ppm (10dKH). pH 6.8 at end of CO2 dose period, 7.8 after 24 hours outgassing.
Décor: Two pieces of driftwood in there since the tank was started in Feb 10.
Fauna: High load: 8 x Rosy Tetra, 8 x Blue Tetra, 6 x Cherry Barb, 4 x Julii Cory, 1 x Oto, 3 x Amano shrinp, 3 x Red Cherry Shrimp, 3 x Nerite Snails.
Flora: Hygrophila corymbosa 'Angustifolia', Rotala rotundifolia, 2 x Crypt. sp., Spiral Vallis, an unknown smaller sword, the remains of the Pogostemon helferi and Lilaeopsis brasiliensis. Also (planted last weekend as part of the post-new-filter revamp) Echinodorus tenellus, Staurogyne repens and Marsilea hirsuta. All plants seem to be doing well except for that Pogostick-plant.
Flow: Filter outlet to full-width spraybar at back top of tank directed parallel to surface towards the front. Good circular swirling flow evident from tracking CO2 mist bubbles. Flow appears to be good in region of Pogostemon.

 

[wearsbunnyslippers]

seems like downoi likes stable water parameters more than a specific range, and even sudden changes like a 50% water change can induce melting.

if you are getting immersed plants, ask what the parameters of the tank that it comes from are, and then try and replicate that, then slowly bring that tanks water into your range, you can then transplant. if you have a spare tank that is...

if you are getting emersed plants then this should not be a problem, see if emersed plants are available?

i see you are using regular gravel, you could maybe also try some root tabs around where the downoi is going to be planted.

are you sure it is dying and not being eaten, rosy barbs and cherry barbs treat this like lettuce...

 

[Whitebeam]

Definitely looked like die-off. The leaves just under the crown went a little brown and sad around the edges, then the stems just seemed to melt. The existing small stems are just sitting there doing nothing. When I uprooted them after, I guess, 8 weeks since planting to shift things around at the weekend, they didn't have any roots to speak of.

The pot I've ordered is the standard Tropica product from The Green Machine. I assume it would have left Tropica having been grown emersed and I would then guess that TGM have been keeping it in stock immersed, but don't know for certain. Any TGM staff reading this, please feel free to comment

Peter

 

[nry]

Any chance it is being affected by the liquid carbon?

PH always tends to grow well for me except when I stupidly tried some snake-oil algae cure which melted the stuff within a fortnight

 

[ceg4048]

What is the pH when the lights go ON?

Browning and melting are a sign of poor CO2.

P. helferi actually does not really care too much about water parameters, or care much about change of water parameters - as long as CO2/flow is adequate. It also typically responds positively to liquid carbon.

Cheers,

 

[Whitebeam]

What is the pH when the lights go ON?

As they go on whilst I'm at work, I won't be able to answer that until the weekend.

Browning and melting are a sign of poor CO2.

That gives me some hope that my new setup will let me succeed where my old one failed then.

My thanks as always.

Peter

 

[Anonymous]

I think it's more about water circulation, this plant needs melts very fast if the water is not moving around it.

 

[ceg4048]

Yes, this is true, however the function of circulation is to deliver nutrients and CO2 to the plant and to take waste products away. With good circulation one can get away with less CO2/nutrients because the delivery system will be more efficient, but you still need to have at least a minimum CO2 concentration level or at least a higher concentration level to compensate for poor circulation. P. helferi is a slow growing stem plant with a high CO2 demand. Once you satisfy this demand it becomes an obnoxious weed;

Cheers,

 

[Anonymous]

Well I've grown it in my low tech planted tank (without CO2), never had any issues with it there. It grows slowly but nice.

 

[Mrmikey]

This plant grows best in my 20l tank that has no co2 and i don't really dose it at all. It grows slow but is a lovely green. In my co2 tank that has hi co2 good flow it seems a little yellow around the tips and isn't as green looking. I'm using flourish iron to see if that helps.

 

[ceg4048]

Well maybe it grows better in the low tech tank due to that tanks lower PAR. I think that's what everyone forgets. Under lower energy the demands aren't as severe. When energy levels are higher the plant demands more CO2.

Cheers,