There seems to be a communication problem here. I'll try to clear things up a bit. It's not impossible to dose MICRO nutrients IF you really need it and eventually find a balance that won't kill your shrimp and/or their young. MACRO nutrients (i.e. nitrate, phosphate etc.) have no space in a shrimp tank, as we shrimp keepers are trying *eliminate* those from our tanks and using plants for that purpose in addition to water changes. Adding those macronutrients back in would really defeat the purpose.
The problem with dosing micronutrients is finding that balance. It's extremely difficult. If you think you have a need to fertilize, ideally you should only dose about enough nutrients that will eliminate the nutrient shortage the plants are experiencing. Considering that plants store nutrients for a while in their tissues, the question is: "How do you know that the plant has run out of nutrients?" Most planted tank people don't wait until their plants start turning yellow to dose. They have a dosing regimen every week. And at the end of the week they usually do a 50% water change to "reset" the water parameters, in case they overdosed. Ideally, you would just dose enough nutrients for the plants' needs and then stop until the plants need more. Unfortunately, there is no device (electronic or otherwise) to determine if a plant has run out of nutrients or if a plant has enough nutrients (after dosing). It's a guessing game.
With plants that might work well, but if you add shrimp into the mix problems *will* arise. Shrimp don't react well to guessing games. By the time you *reset* your water parameters, the shrimp will have accumulated all kinds of fertilizer ingredients in their bodies. With shrimp, things like heavy metals and minerals don't just pass through their system, a large part just keeps getting accumulated in their bodies until some of those things become too plentiful and harm the shrimp. This happens over time, so you won't necessarily see an immediate reaction when you start dosing fertilizers (or put shrimp in a regularly fertilized tank). However, after a while you'll start seeing a dead shrimp here and there, whereas others seem unaffected (still accumulating chemicals in their bodies). Even if the adults do ok, hatchlings are even more sensitive to adverse water parameters and die even more easily.
As sensitive as shrimp are the risks of adding fertilizers to a tank is just too large to recommend such a practice. Yes, there might be some reports of success with hardier species (such as amano shrimp) and maybe even reproduction reports with species such as the red cherry, especially in lightly, irregularly fertilized tanks, but most of those reports are short term successes and exceptions. After all, in a guessing game you can get lucky too.
More below...
Dusko wrote:
Soil plays a big roll in plant fertilisation.
Not in most true water plants. Most true water plants take up nutrients with their leaves and bodies. However, lots of swamp plants are being sold as water plants in the aquarium hobby, so people think that these plants normally grow inside bodies of water all year round. If you grow and Amazon sword above water, you'll see that they are much easier to grow then submerged. That's because they are not meant to be fully aquatic. Hence, plant farms grow most of their plants above water. Fully aquatic plants are not as fussy about nutrients and are usually easier to grow.
Your plants are thriving not because of your shrimp waste but because your tap water is Hi in nitrates and phosphates + trace elements.
I don't know where do your plants get their Iron supply though.
Fish food and shrimp excrements provide more than enough macro and micronutrients. You might want to read the ingredients list of the fish food you're using. Tons of chemicals in there. That's why I recommend feeding those prepared foods sparingly since they release tons of chemicals into the water and may *overfertilize* the water to a degree that shrimp start dying.
"My plants are for the shrimp, not the other way around." you said.
I rather believe that any living creature (plant or shrimp in this case) deserves the same amount of respect when kept in captivity by us (humans). They didn't choose for them selves to end up in our tank. I believe that your shrimps look upon the plants like their friends.
Since this is a shrimp forum the focus is on shrimp and not plants. This has nothing to do with respect. We use plants to keep our water parameters constant and eliminate potentially harmful things like nitrates, phosphates, heavy metals etc. from our aquaria. That's why we usually use fast growing, non-finicky plants such as Najas, horwort, various Egeria sp. etc.. You seem to be a planted tank person first and foremost and your focus is on your plants. Shrimp are probably just a "clean up crew" for you (even though your focus might change over time

). So, as you can see, it's all about focus, not about elevating one creature over another.