Originally Posted by Seattle_Aquarist
It looks like 'green water' to me. You dosed extra KNO3 before you left, did you by any chance feed 'extra' food as well (which break down into nutrients?
Just an FYI if I'm going to be gone for two or three days I feed my fish normally the day I leave and I feed normally when I return. I don't dose extra nutrients for the plants.
If gone for over 3 days I have a 'fish sitter' come in and dump a pre-measured baggie of food (regular daily amount) every three days. I cut back the photoperiod on my tank by 33% - 50% and don't dose plants at all. Other than trimming when I return, and the fish being skinny, I seldom have any issues.
Ugh. Green water. I can't remember if I fed my fish or not before I left. Probably did a little (I feed every other day). My KNO3 levels were about 10ppm before I left, so thought I'd dose some to get through a couple of days. KH2PO4 was >5ppm, so didn't dose any of that. Didn't think I needed to shorten the photo period. Figured there were enough nutrients in the tank and I'd be back in a couple of days.
I'll admit the water was starting to cloud a week ago. I thought it was from some of the dosing additions. It is what it is now.
Yep that is green water, a light form, but those are definitely algae in there. Do a big water change and keep the UV going about 2 weeks. That will get rid of it.
With a high GH you will usually have enough Mg. Even so, above 3mg/L Mg all symptoms have disappeared. So add enough MgSO4*7H2O to get 3mg/L Mg in your aquarium and you are good with that part. Pay attention, epsom salt is MgSO4*7H2O not MgSO4. It will make a difference in the amount you need to add.
In the pictures I see signs of PO4 deficiency and maybe micros. R vietnam will surely respond positively when enough micros are present. I will suggest something crazy. Take your test kits and put them in a box or a drawer and not use them for 3 months. Instead add enough nutrients for the plants to grow, something like 3mg/L PO4 20mg/L NO3 ... is enough for most aquariums. Do a weekly 50% water change and your nutrient values will not be to high to cause any troubles with fish or plants. During these 3 months you will get to know how plants look like when they have plenty and how they tell you what they are missing. You will also save a lot of money on test kits
I did it, and I see it so often that somebody start something similar to EI but then start coming back to old habits of trusting test kits and making decisions based on what they tell you.
It's funny you mention K2PO4 deficiency because those levels are always higher than what "guidance" says they should be. I have a decent fish load which provides PO4, so I'll dose half EI some days of the week. Like I mentioned before, the test kit said PO4 was at 5ppm yesterday. Back to full EI. Honestly, I haven't tested in months. Could always tell something was off because growth wasn't that great. Micros get full EI dosing. I have an Sera Fe test, and at the end of the week, it's crazy high.
I'm on the right track with adding Mg. Change in plant growth was very noticeable once I added extra (beyond the gH booster I was adding). And the r. Vietnam is starting to put on decent looking new growth, which it never has. Hopefully will get the green water cleared and can further tweak from there in the next week or two.
50% water change was completed last night. UV is running. Just dosed full EI.