Hi Jaap,
I have had a good look through this journal. Isn't it frustrating when you think you are doing everything by the book and you still get problems with algae
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Even with the advice from everyone from UKAPS and reading all the threads on algae no matter how experienced we think we are, we still get problems with the dreaded algae!
So what is causing your problems? I see you have had some input from Clive. Clive has helped me out loads of times and I have always followed his advice and he has been right almost 100% of the time. He is absolutely right when he says nutrients don't cause algae.
Algae is caused by excessive light over too long a period. Full stop.
So what would I do now in your situation? For what it is worth here is my humble opinion.
The way I see it, for this tank you have two options.
1. Stick with it, work out how to deal with it and learn from the process so that you develop your knowledge to prevent it happening again next time you set up a new tank, or,
2. Strip the whole thing down and start again.
From the last photograph above it looks like you are making some progress, definitely moving in the right direction. From the earlier photographs it looked to me like you were adding too much Macro and Micro nutrients for the amount of plant mass you had in the tank and definitely too much light too early in the tanks development.
The stem plants looked long and leggy, I would have been pruning these back and re-planting the cuttings to thicken up the plant mass. The stuargyrene repens plants looked stressed and weak and were not strong enough to absorb the nutirents you were adding or make effective use of the light you were using.
So if you have got weak and damaged plants with leaves melting etc, you are chucking in loads of nutrients and using high intensity lighting over too long a photo period, something else has to take advantage of these conditions, have you guessed what it is yet? Yep, algae
So with weak and stressed plants you then started double and treble dosing with Seachem Flourish Excel trying to kill the algae but finished up stressing out the plants even more. Also one of the things that caused your problems was that the plants were trying to grow above the substrate before they had chance to put down a really strong root base. If you are using a substrate which is neutral and contains no nutrients or fertiliser whatsoever, the foliage above the substrate might be getting nutrients from the water column but without a healthy root system to support them the plants are going to struggle.
If I had been in the same situation as you were in here is what I would have done. It is not too late to do this now either.
1. Reset the water column back to zero. By this I mean do 3 x 50% to 80% water changes over the period of a week. Do this until you are absolutely positive that you have removed all traces of Macro and Micro nutrients. (I have no idea what your Nitrate/NPK levels are but I am guessing they were off the scale because your plants were not healthy enough to make use of them)
While you are doing the water changes physically remove by hand as much algae as possible. Use a pipe cleaning brush and twirl it through the plants to trap and remove as much algae as possible.
2. Temporarily suspend the use of EI or adding any fertilisers into the water column. If your substrate is neutral buy some of the best quality plant root fertilser tabs you can find, (
not the big round clay balls from JBL) and push them into the substrate all around the plant base. Trim and prune the plants, especially the leggy stem plants and re-plant them.
3. Cut out all of your lights for at least one week. A total blackout covering the tank might be too much but at least leave all the lights off and give the roots some time to find the nutrients in the root tabs and establish themselves.
4. Stop using Floursih Excel or dumping any other chemicals (peroxide or anything else) into the water.
5. Looking at the pictures of your spray bars the flow around your tank looks more than enough to me, maybe even a bit too much. You just need to make sure the CO2 is being picked up and moved with the water. HOWEVER and this is just my opinion, there is no point in cranking up the CO2 to the point where your drop checkers turn to a lemon yellow colour, or to the point where the CO2 is so high it is killing your amano shrimp and your fish, ESPECIALLY if the plant mass is so low in the first place, it is just a waste of your CO2. As the plants increase and establish themselves you can increase the levels of CO2 and gradually re-introduce the lighting, and if you want or feel it is the right time start re-introducing the EI Ferts.
I have had good and bad experiences with EI. When you get the balance right between water quality, lighting, plant mass, fish stock and the right EI dosing regime the results can be spectacular, get it wrong like I did (this was totally down to me) it caused me quite afew problems. If I was giving anyone advice who was just starting out using EI, my advice would be to calculate what you think you need for the size of your tank and the amount of plants you have, and then halve the dose for the first few weeks to see how it goes. The plants will tell you if something is not right, and you can always increase slowly over a period of time to see how the plants adjust.
6. Remember two things, 1)The only things that happen quickly in aquariums are bad things, and 2) The only things that happen quickly in aquariums are bad things.
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Best of luck with it.
Cheers,
Steve.