Help Hard time getting rid of gda, diatoms

[CincyScaper]

This makes me wonder if my aquasoil is just depleated... It's about 1 year old, but the first 2 months were dark start and there were a few additional months that the filter was running but with no light and no plants. It never saw a plant load heavier than the last few photos (so fairly light/medium). I have never added fresh aquasoil or root tabs. I did use the pellets that come with Amazonia II, and they're still in good shape. Our apartment does get quite a lot of natural light, but I measure the corner where the tank lives at about 10 PAR at its brightest.

What you described also makes me question what I thought I knew about algae management, and my brain is full of somewhat conflicting information.

Regarding aquasoil, part of me seems to believe that since people keep plants in inert soils, then you should be able to treat depleated aquasoil just like an inert soil by dosing more nutrients to the water column. I know that this is wrong, but I don't have enough information to change my framework to something more accurate.

Likewise, many people have emphasized that "exceess nutrients don't cause algae" and that algae indicates something is out of balance (namely lighting, CO2, nutrient stability). In some ways this has led me to believe that nutrient levels don't really matter as long as they're stable and not crazy excessive, and that any algae problems are a result of lighting or CO2 not being correct for a particular nutrient level. Yet again, I know this is wrong. Dennis has a great article on this explaining how high nutrients are not appropriate for all tank types.

Do excess nutrients trigger algae growth in a planted tank?

Debunking the myth of 'Excess nutrients' as the principal trigger of algae growth in planted tank.

www.2hraquarist.com

Yet, with such little experience, I find myself battling these innacurate mental models in trying to figure out how to address the issues in my tank.

TBH one of the nice things about Scapecrunch is that the information is consistent.

Dennis has lot of great articles and lot of people have great articles at Scapecrunch as well, but to quickly summarize,

Stability is the key when it comes to nutrients.
You have to decide whether you are going to do EI (Water column fertilizer - Nitrate level consistently at a high level) or Lean dosing (Almost Zero nitrates in water column, but have a rich substrate either by placing root tabs or replinishing aquasoil - Dennis also calls this Zero bound system since one doses the WC the same as the plant absorption so essentially the nitrate level is always stable close Zero - this is the approach I do and you can read about this in my journal as well). You could also do a system where the nitrate is somewhere between them both where the nitrate level is stable but not very high as in EI, i do not have experience with this.

The fact that your new growth looks good tells me that things are going well and you just need to give it time. With the lean dosing growth rate is slower as the aquasoil depletes. But if you are seeing good growth but just slow i would look at this as an advantage for less maintenance.

As i mentioned before, i think you are neither doing EI or lean dosing and you are somewhere in between (with big dosing after WC) and that might be one of the issues with the nitrate stability and it might be worth checking nitrates with a different equipment. @Naturescapes_Rocco has a nice nutrient accumalator calculator that you can looks us as well to see if your nitrate level is stable.

My only other thought for you, which might be slightly off the usual advice is that focusing on getting plant mass might be more helpful at your stage rather than getting rid of algae. Meaning just let everything grow out real dense without doing too much replanting. But i do highly recommend reducing the PAR level to close to 50.

Just my 2 cents.

 

[ScaperHaynes]

As i mentioned before, i think you are neither doing EI or lean dosing and you are somewhere in between (with big dosing after WC) and that might be one of the issues with the nitrate stability and it might be worth checking nitrates with a different equipment.

You had a great point that I seem to be somewhere between lean and EI. I also think you may be onto something about letting things grow out a bit more instead of constantly pruning and replanting in attempts to fight algae.

I lowered the PAR to 65 this week (this is as close as my light dimmer will let me get to 50), and aimed to stay <1-2ppm nitrate. The growth was slower, but there was very little algae growth and it made tank maintenance much more managable.

I also measured nitrates every single day instead of just blindly dosing and hoping for the best.

The attached screenshot is a spreadsheet comparing nitrate tests every day and the tank growth at the beginning and end of the week. All fertz were dosed before the photoperiod, and all nitrate measurements were taken after the photoperiod ended each night.

This tank appears to only need about 3ml or less of APT 3 week to keep the nitrates <1-2ppm. My dosing propably looks sporatic, but I was only responding to what the tests were telling me and I plan to spread dosing more eveningly next week.

Any feedback on this? It seems like an extremely low consumtion rate for a high-tech tank, but then again the plant mass isn't all that dense yet and I have little context as a beginniner. The plants also aren't pearling as much anymore with the change in parameters, so that makes me worry a little.

I haven't ignored Dennis' advice to experiment with raising lighting levels since the plant mass is thin, but I'll have to run that experiment after my wedding because I just can't keep up with the faster growth rates right now.

P.S. I replaced all my Hydrocotyle Tripartita with monte carlo this week so that's all still settling in.

 

[CincyScaper]

If this is the API kit, it cannot measure low levels (< 5), so might not be the best to rely on that unless you are somehow altering the test.
Your plant growth looks ok to me. Pearling is a good sign, and going by plant health is the best way. In a relatively older aquasoil that does seem like a pretty low dose of APT 3. I would recommend just dosing what Dennis recommends which is probably around 2 ml/day for your tank.

 

[ScaperHaynes]

If this is the API kit, it cannot measure low levels (< 5), so might not be the best to rely on that unless you are somehow altering the test.
Your plant growth looks ok to me. Pearling is a good sign, and going by plant health is the best way. In a relatively older aquasoil that does seem like a pretty low dose of APT 3. I would recommend just dosing what Dennis recommends which is probably around 2 ml/day for your tank.

Even when I’ve dosed only 1ml/day consistently in this tank I’ve gotten a huge amount of algae, so that’s part of the struggle.

What also doesn’t line up is that APT3 is supposed to be zero-bound. While the API test kit isn’t great for distinguishing 1-5ppm of NO3, it can detect zero pretty reliably and my tank isn’t bottoming out at the end of each day even at 1ml of APT3/day or less.

Dennis’s calculator has the option to select the “Low plant mass? Mostly shade plants? No co2”, and I’ve always been confused as to whether or not one or all of those things need to be true to select that option. I’ve been assuming that it applies to my tank due to the relatively low plant mass, hence the reason I lean towards a smaller dose than the 2ml/day standard dose for a high tech tank.

Either way, when I dose 2ml/day, my nitrates climb throughout the week and are not zero bound. I also get lots of algae every time I’ve dosed 1ml/day or more.

 

[ScaperHaynes]

This week I tested NO3 again every night after the photoperiod. But! I dosed the same amount of APT3 each morning instead of attempting to use the nitrate test to chase a daily bottoming-out of NO3 like I had the week before.

Overall, plant growth and pearling was much better and new algae growth was pretty minimal throughout the tank. However, there are a few things that intrigue me about these results.

When I'd tried this daily dose (1ml/day for 60L) before with higher light, (95par vs 65) I got way more algae. Not sure if that means I was under dosing or over dosing.

It's also curious that APT3 @ 1ml/day in a 60L tank should = ~.55ppm/NO3 per day, so it's odd to me that the nitrate reading at the end of the week seems most similar in shade to my 10ppm reference solution. Even if no NO3 were consumed, there should be a max of ~3.3ppm NO3 in the tank. Maybe it's just the lighting or a test kit accuracy problem, but I plan to re-test this with a Hanna checker when I get one. (Edit: While my test this week was taken under the same lighting and background every time, the lighting in that room is very warm causing the readings to look much higher than references. The color darkening is magnified by the vial being placed directly against the card. These factors may explain this descrepency in expected vs measured results. See next post.)

Based on my last post, my nitrates were clearly climbing throughout the week despite very sparse dosing, but plant health/growth didn't seem that great in comparison to this week with consistent dosing and nitrates climing each day. This makes me wonder if NO3 isn't the limiting nutrient for whatever reason, like uneven aquasoil depletion, etc. where phosphate may be the limiter.

Some Questions for @Dennis Wong :
Your article on nutrient stability states that in a zero-bound system, you should aim to keep nitrates at 5ppm and below after water changes. However, I thought I'd read elsewhere that a zero-bound system should bottom out daily. Did I misunderstand something here?

Is it reasonable for me to be dosing slightly under the recommended dose for a 60L tank (1ml vs 1.8ml) until my plant mass fills in more? Per my discussion with @CincyScaper above, I didn't want to end up in no-man's land where I'm neither doing lean dosing or EI.

Any other insights you'd add based on these test results?

 

[ScaperHaynes]

For the other curious minds out there... This was the same exact water sample with the photo taken under warm indoor lighting versus outdoors with natural daylight, taken less than 1 minute apart. The water sample was from my post 80% water change, so it would be easy to be misled into thinking I'd overdosed my tank significantly based on the first photo due to the warm lighting throwing off the color.