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Help! Stunted growth / old growth browning - Low Tech

CARLOSII22

Seedling
Joined
15 Jul 2020
Messages
2
Location
London
I hope everyone is doing well. I have done a lot of reading across the forum to try and troubleshoot the issues I am having, but I am currently struggling with stunted plants and old growth dying off in my low tech tank (no pressurised CO2, no liquid carbon). It has an inert gravel substrate, so I think I may need to water column dose even more than I have been. I understand from reading various posts that nutrient rich substrates aren't necessary if the water column is sufficiently dosed.

I suffered for a long time with no growth at all on all of my plants. Since I upped the magnesium and potassium dosing I have definitely seen a lot of improvement with new growth, especially on my Java ferns and Dwarf sag. I am however still noticing that old growth is turning yellow/brown and dying off on my L. Sessiflora. The new leaves on the majority of my rotala stems are also very small, what is strange is that a select few stems are growing nicely. Likewise with the L. Sessiflora, one or two stems remain a lush green but the remainder only have lush green new growth. I had a decent carpet of S. Repens growing, but the old leaves were dying off and then being attacked by BBA so I cut it all back and replanted, but have yet to see it come back to life.

Please see my tank / water parameters below. I have added some Salvinia to a breeder box to do a duckweed index check and I am seeing the same thing, there is new growth, but old growth looks to be dying off/melting. I think this is a potassium deficiency, but I am keen to hear everyone's thoughts. As it is old growth that is affected, I think it is a mobile nutrient issue. I have ruled out N and P based on testing and the fact that I have high fish stocking and only a moderately planted tank. K and Mg were the other two possible reasons, and I am dosing these now at 10.5ppm and 5.6ppm respectively per week which did help, but I am wondering if I need to dose even more K. With spray bars across with the length of the tank I have good flow around the tank with plants at the substrate level swaying in the flow and a light ripple at the surface for gas exchange.

[Edit]: Changed the format of the information below to fit with the forum guidelines:

1. Size of tank: 275L, the tank has been running for 5+ years, but has only been planted for the last 4 months, temp = 26°C. Water Parameters: pH ~ 7.8, Ammonia 0, Nitrite 0, Nitrates 25ppm, Phosphates >3ppm (based on calibrated Salifert test kits)
2. Filtration: 2x Fluval 404 filters with spray bars across the length of the tank, each filled with DIY coarse, medium and fine sponges, followed by filter floss and then 1.5kg of biohome ultimate and 500g of ceramic media. Total biofiltration = 4kg
3. Lighting and duration: 2 x 40W of T8 lighting for a continuous 9hr lighting period. In the past I tried upping this but that resulted in BBA on old dying leaves
4. Substrate: Inert Gravel
5. Co2 dosing or Non-dosing: Non dosing pressurised CO2 or liquid carbon
6. Fertilisers used + Ratios:
a. Daily Fert Dosing:
1.5ppm K (10.5ppm total per week), 0.8ppm Mg (5.6ppm total per week),
b. Weekly Fert Dosing: Micros to achieve 0.1ppm Fe with a mix equivalent to the APFUK chelated trace. I know I most likely have a iron deficiency because my tank pH is ~7.8, I have ordered Fe DTPA and Fe EDDHA to help with this and will dose 0.1ppm of each when it arrives
7. Water change regime: 30% weekly done with London Tap water which is quite hard, pH ~ 7.8, Ca++ 100ppm, Mg++ 5ppm.
8. Plant list: S. Repens, L. Sessiflora. Rotala Indica, Rotala Rotundifolia, Java Fern, Java Moss, Christmas Moss, Helanthium Tennullum, Dwarf Sag., Lobelia Cardinalis, Crypt Wendtii Brown, Anubias Barteri, Salvinia Natans
9. Inhabitants: 20 x Neon Tetra, 20 x guppies (various sizes), 7 x Ember Tetras, 6 x Glowlight Danios, 5 x Coral Red Platies, 1 x Safron Molly, 1 x long fin Bristlenose Pleco, 100+ x Red Cherry Shrimp, a few mini ramshorn snails.
10. Full tank shot: Posted along with some photos of the issues I am facing.

Please let me know if any further info/photos are needed, apologies for the slightly blurry images, the bow front makes it difficult to get good photos.
 

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I'm currently running a low tech tank. I suffered with stunted growth and die off. I found my water temp was quite high so I turned my water heater down and run my tank at about 24 degrees. I also added capatta leaves to bring the ph down from between 7.6-7.8 down to 6.8-7.2 great food for shrimps as they decompose. I also do larger weekly water changes so I will remove between 50% up to 75%. I have hard water in the west midlands. So far i've managed to turn all the plants around and growth has been stable since. I run to t5 40watt lamps on 8hr photo period. Low tech growth is very slow and some plants like anubias are slow growers by nature. I've even managed to get some medium cat reneickii pink to grow in low tech set up. I have used tropica soil substrate for the majority of my plants because some plants are still root feeders crpyts and echnidorous are examples they build large root systems.

I would try using a base layer substrate under your inert gravel so plants can pull nutrients with roots as well as the water column
 
Hi all,
1.5ppm K (10.5ppm total per week), 0.8ppm Mg (5.6ppm total per week),
b. Weekly Fert Dosing: Micros to achieve 0.1ppm Fe with a mix equivalent to the APFUK chelated trace. I know I most likely have a iron deficiency because my tank pH is ~7.8, I have ordered Fe DTPA and Fe EDDHA to help with this and will dose 0.1ppm of each when it arrives
If your plants are iron (Fe) deficient it will take them a while to perk up, because iron isn't <"mobile within the plant">.

It definitely looks like you have some deficiency symptoms in the older leaves. I say this because your Salvinia, <"which isn't CO2 limited">, is showing damage to the older leaves. It is really difficult to diagnose deficiencies of a mobile nutrient, but it is possible that your water supply has been through a <"phosphate and/or nitrate stripper">, and these are two of the three macronutrients.

I'd try a complete fertiliser for a while and see what happens.

cheers Darrel
 
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I'll add my vote for lowering the temperature. Check seriously fish for your stock and drop to the low end of their range. I (slowly) took my low tech tank down from 25 to 22, which helped my plants without adversely affecting the fish.

I also cut over to eddha Fe, and saw a difference pretty fast in my floaters (I am a slightly modded 25% APFUK EI dose for macros).
 
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