[dwalstad]

Thanks. Very helpful information, and the best thing is that you have shown us that it works!

What I like is that this iron product is readily available and does not contain any other stuff--NPK, sulfates, other micronutrients. Note that gluconate is also sold to humans as the calcium supplement 'calcium gluconate', a form of chelated calcium. Thus, it is totally harmless and bacteria would be expected to break down the gluconate as they would DOC. FeEDTA will also work, so pricing and availability would be main determinants for these products.

Here is product information from manufacturer:

"Flourish Iron is a highly concentrated (10,000 mg/L) ferrous iron gluconate supplement. Plants are able to easily derive a benefit from Flourish Iron because ferrous iron gluconate is already in the ferrous form so they do not expend energy reducing it. Despite what other manufacturers may intimate, gluconate is not harmful to plants or fish. In fact, ferrous gluconate is better suited to foliar feeding than is iron-EDTA, owing to the relatively weaker iron-gluconate bonding vs. iron_EDTA bonding. In addition, ferrous gluconate has the added bonus of being a source of carbon."

 

[Oslo]

Last update. my floaters grow slowly, but have a nice green color after Fe supplement. In contrast, my H.polysperma grow like crazy (see pictures).Can the reason for the slow growth of the floaters be explained by lack of ammonium in the tank? Water contain enriched levels of nitrate and no ammonium or nitrite.

 

[Oslo]

So, back to the gravel size. In my current tanks I am using gravel size of 1-2 mm resulting in a lot of debris on top of the gravel cap layer (food, fish poo, plant debris etc). Should I do regular vacuum gravel cleaning or should I just let it be? It is not that easy to vacuum clean the gravel in a jungle planted tank......

I currently looking at different gravel sizes as a cap for a garden soil in small tanks. Gravel sizes 1) 1-2 mm 2) 2-4 mm and 3) 4-9 mm.

Do you think I will be able to measure any discrepancy in water parameters between the "tanks" after some weeks/months?

 

[dwalstad]

You'll have to be the judge and jury in your experiments. Will be interested to see your results and conclusions.

I would just leave the debris on the bottom. Only if it gets to a depth of 1-2 cm (0.5") or you see problems would I consider vacuuming.

I wouldn't worry about nitrogen in your tank. If you see yellow leaves, that's N deficiency. If N was limiting, you wouldn't be getting such spectacular stem plant growth.

Interests me that your H. polysperma started growing well after the iron fertilization. For my tanks, I am wondering if--in the past--iron limitation held back not only my floating plants, but some of the nice stem plants? (I had assumed it was CO2 lack.)

Allelopathy between H. polysperma and floaters could explain restricted floating plant growth. Plants compete in mysterious and weird ways!

 

[Oslo]

Thanks for your reply, I will leave the debris alone then. It does not look so great with debris at the bottom, but it is not easy to remove the debris either without seriously disturbing the plants. Yes, I am not sure what is going on either, as mentioned the H.polysperma and N. hydrophylla "Taiwan" grows fast, while the floaters, which grew really fast in the beginning are now growing slowly. Another plant that grows slowly is the Red Tiger Lotus (Nypmhaea Zenkeri), and the red Alternanthera Reineckii seem to slowly die (not grow at all). Further, Hygrophila corymbosa is not growing much either, but it is still there, so it is not dying either.
Would have been nice to be able to measure CO2 levels, but I guess you need expensive tools to do that. I think maybe the floaters grow faster with excess of ammonium and nitrite than nitrate? Do not know if iron affects the growth rates of the floaters or the H.polysperma. Maybe it was fish and fish food that increased the growth of H.polysperma.

Anyone had nerite snails in a tank? They seem to lay white eggs on the tank walls and some kind of white slime/mucus that does not look so good. I will try to take a photo of it.

 

[johnwesley0]

In My Opinion (IMO), floaters tend to grow by multiplying separate plants. Once they've run out of room at the surface of the tank and are actually touching each other, they don't get any bigger they just age in place and any excess ammonium/ammonia is taken up by bacteria. That's why your nitrate levels are so much higher than the other nitrogen levels.

 

[Jorge Soirse]

Anyone had nerite snails in a tank? They seem to lay white eggs on the tank walls and some kind of white slime/mucus that does not look so good. I will try to take a photo of it.

I don't keep nerites. My problem is usually lack of algae, not the opposite. However, it is my understanding that they lay eggs but they can't hatch, they need brackish water for them to be viable.

 

[Oslo]

What kind of shrimps would go together with guppies in a low tech dirt tank?

 

[mistergreen]

I‘d keep amano. Pretty good hair algae eaters and too big to be eaten.

 

[Oslo]

So, after about 2 weeks after setup we can observe two things by looking at the pictures.

1, Different levels of tannins (organic materials) in the water layer.
2. A water surface membrane can be observed in the bottle that contain the highest amount of tannins

 

[dwalstad]

Your experiment suggests that the leaching of nutrients into the water is faster with a cover's greater particle size. That makes sense. A larger particle size allows faster exchange between water and soil. This can be good as it allows greater aeration of soil layer. That's why I advise making a sand cover as thin as possible in order to encourage this beneficial exchange.

 

[Oslo]

Did a JBL strip test yesterday and it seems like the strip to the far right has a slightly higher pH and GH/KH (from the sample with the largest gravel size 4-9mm).
Will do more water tests during the week.

 

[Oslo]

So, first the good news, my floaters look good in all three tanks. No more yellow/pale floaters, cured by adding iron to the water layer.

Then the bad news, it looks like I have another nutritional plant deficiency in one of the tanks? The question is what do I lack? After testing the water layer with a JBL test kit it seems like the water layer contains enough NO3, PO4, iron and K. Still my H.polysperma is loosing its older leaves and gets nasty spots (see pictures below).

 

[dwalstad]

If I were a H. polysperma under that floating mat, I would be very unhappy. The submerged plants are losing out to the floaters in terms of light and nutrients. Who knows if allelopathy is involved as well?
I would remove floaters so that they cover only half the water surface.
[On a technical note, it would be easier for me to follow your thread if there weren't so many repetitive high-resolution pictures that I had to scroll down through.]

 

[Oslo]

I have another question also, if I have a lot of PO4 in my water layer due to excess of fish food, what happens then when I add ferrous iron gluconate from seachem? I will probably get iron phosphate precipitate at the bottom of the tank? Resulting in less free iron for the plants? I did a JBL test, and my test results showed a less positive iron signal in the tube where I had water containing KH2PO4 supplement.