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Discussion Starter · #1 ·
Thought I'd share my experience and a few lessons learned in case it's useful to anyone else. This will be long. It will be much more useful (if it's useful to anyone) for non-experts and "typical" aquarists than others. I would welcome feedback, especially as it relates to things going forward.

The Basics:
  • Freshwater aquarium
  • 40g Breeder
  • 36" Fluval 3.0 light, 18" off the substrate.
  • Zero sunlight, a little bit of ambient overhead lighting while the lights are otherwise off.
  • One HOB filter (with bio media and a crushed coral bag, but no carbon or chemicals), one sponge filter.
  • One inch layer of eco-complete underneath medium-size natural-looking gravel.
  • A moderate to heavy population of mostly small, community fish.
  • Current plants: bacoba caolinia, rotala repens, jungle val, dwarf sag, two compact amazon swords, and a couple petite anubias. Moderately+ planted I think.
  • Current hardscape: a couple large and three or four small pieces of quartz, medium-sized centerpiece driftwood, a few smaller piece of driftwood.
  • Typical params: 76 degrees, pH 6.4-6.6, gH and kH both 4-6, nitrates typically <10, effectively 0 phosphates, and tap water is high in silica, but used straight out of the tap with conditioner. Tends to be very stable without a lot of effort.


I set the tank up 2 years ago and avoided a lot of the the beginner mistakes. Didn't crash the tank, fish did well (once I started drip acclimating). Plants generally did OK at first, but didn't thrive. Tall grass got flat black algae that expanded over time. Moneywort too. Compacts got that later. Cabomba grew like crazy (though bottom 'leaves' died out on each stem) and I wasn't good about pruning. Dwarf grasses slowly died. Not a lot of algae anywhere else, but tank slowly declined. Fish were fine, with only normal attrition.

The real trouble started when I cut the Cabomba back like 90%. In hindsight it obviously destabilized the tank. From that point forward it felt like I was always a couple steps behind. No matter what I tried, algae kept getting worse. It was depressing. (Lesson learned: be really careful changing the plant mass in your tank suddenly!)

2020 was a rough year (even without COVID) and the combo of being very busy elsewhere and the decay in tank led to it getting out of control. Like ****ty-tank meme bad. Algae completely took over. Everything. Piles of loose algae on the bottom, hardscape covered, glass covered, equipment covered. It was really really depressing. And overwhelming. I had to decide whether to get rid of the tank or start again.

I suspect a lot of other beginners get to this point, and this post is for you. If you're willing to work, don't quit. I'm convinced it's not magic despite the fact it feels like it sometimes. But especially if you're at the point I was it will be a LOT of work. I still don't have things in perfect harmony again or anything (see below), but I do have my tank back, it looks good to casual observers, and it's trending in a good direction. (Side note: It doesn't have to be a lot, but you should be doing something each week. It's 25x harder to recover the tank than it is to just keep up with it.)

Try Try Again

So starting a couple months ago I rolled up my sleeves, started taking all of this more seriously, did a lot of reading, watched a lot of videos. Tried to cut things down to size.

At first I was just doing 20-25% water changes a couple times a week, scraping algae and then removing the scrapings and the piles of loose stuff from the tank. Plus vacuuming out the bottom over and over. It probably took 6-8 changes until all of the loose algae piles were gone and the tank started to feel "clean". The algae I was getting was mostly brown diatoms I think -- I'd remove them, but then they'd resettle. I didn't even bother with the black/green beard algae at this point. In hindsight I think this was the right thing to start with. Just getting the "easy" algae off the glass, off the bottom, and out of the tank as much as possible while keeping the water clean. I also cleaned the filters a couple extra times during this stretch just because there was so much stuff being sucked into them. Doing this let me see the bones of the aquarium again and was encouraging -- it was a lot of immediate bang for the buck.

I also did a ton of research on algae. Not just because it was out of control right then, but because I'd had it even before the collapse and it slowly choked my plants to death. I wanted to understand why that happened. First, the Bad News: advice on algae is all over the place. No one really has a one-size-fits-all answer. "Experts" contradict each other (with great gusto and certainty and passion). It's confusing. However, the Good News is that I think there are some basics that will work for everyone and, as long as you're not looking to build an 8k cinema-quality, award-winning, densely-planted jungle, you can most likely get algae under control at least to the point it's not ruining the experience. I am not an expert, so take what follows for whatever you think it's worth.

The only thing everyone agrees on is this: you get (significant) algae when lighting and the nutritional needs of plants in the tank are out of balance. The range of nutrients your plants require to survive/are able to use drives the amount of light you need, as long as you have the minimum needed. And the amount of light you have drives the amount of nutrients you need, again as long as you have the minimum required. Up to some maximum, one or the other of those inputs is limiting the growth. Lower light = lower nutrient need; higher light = higher nutrient need. And vice-versa. It is pretty hard to get this perfect, especially once you're already having issues. More on this later.

After watching and reading a million algae videos and reading every 21st century forum post on algae I could find, here's what most of the solutions have in common:
  • A cleanup crew is invaluable. Sucker mouth cats, especially tank-appropriate Plecos and Otos; Snails; some Loaches, some shrimp, tank-appropriate Chinese/Siamese algae eaters, Flagfish. (My dwarf gourami grazes on plant detritus, including the BBA tufts on the bottom of the tank.)
  • Good tank hygiene is really important to controlling algae. Clean the glass. Manually remove algae if you can during cleanings. Vacuum. Keep the filters clean. Do regular water changes. 99% of this is basic stuff you should be doing anyway, but it helps control algae too.
  • Healthier plants and more plants help keep algae down. If your plants are healthy and thriving, algae will find it hard to compete with your plants for nutrients and light.
  • Match your nutrients to your particular plants' needs and your vision for your tank and then tinker with the lighting until you get it right. No one said it exactly this way, but to cut through the chicken-and-the-egg nature of nutrients and lighting levels, I decided to start with the nutrients, and then match the lighting levels accordingly. So If you have a jungle and you want it to grow fast, use max nutrients, do big water changes and you'll need a lot of light. A moderately planted tank that you don't want to prune a lot requires less nutrients and, therefore, less lighting. Start with the type of plants, the volume of plants, and the desired growth rate, introduce the appropriate level of nutrients to do that, then dial the lighting up and down until you get it right. It's the mismatch between nutrients and lighting that causes problems -- so if you can get the nutrients right (see below) the lighting can follow. (If this is wrong, I hope someone will correct me.)
  • There are more invasive, more radical, things you can do. I'm not going to talk about those here because I hope not to use them, opinions are more mixed, and some of them can kill fish, invertebrates and plants. (Having said, hydrogen peroxide comes up a lot as an effective, relatively safe method.)
  • Finally, you didn't get into the mess you're in in a week or two and you're not likely to get out in a week or two. Mentally prep for a longer battle. Be patient.
With all this in mind, I was ready for the next steps in my reclamation. Brown algae continued to grow during this period, but I was keeping up with it during water changes. And I hadn't touched the black beard algae at all yet, and it was still spreading. So those were my main concerns before repopulating the tank.

First I removed the hardscape and equipment and bleached it in a very light solution for 48 hours. Maybe 3% bleach to 97% water and then scrubbed it with a hard brush and let it sit for 24 hours. I won't try to do the chemistry here, but bleach is fine with three important caveats: I only used it outside my tank, I didn't use bleach on my filter or related sponges/bio media, and I rinsed and air dried everything for days before putting it back in. I've read some of the rinsing and drying isn't necessary, but I decided to err on the side of caution. I am an idiot, so I'm fond of idiot-proof methods. I also manually picked out individual piece of gravels that had BBA tufts on them. I didn't get them all, but probably removed at least half, one at a time, picking out some each time I was in the tank to clean or to plant.

I also introduced plants back into the tank. Quite a few (see above). I'm not going for a full aquascape or anything, but I wanted a fairly heavy plant load.

Then I added six Otos and reintroduced the snails I'd lost over the last year. (I already had a Bristlenose Pleco and some Corys.) I can't say enough about the Otos. I know they don't eat every kind of algae, but they are absolute MACHINES when it comes to the two types I was facing. I'd stopped clearing algae for a week before they were added to the tank (to make sure there was algae for them to eat) so the brown algae was back and the BBA immediately re-covered my rocks with a solid carpet on the sides getting light and attacked the compact swords and dwarf sag. Depressing! But less than two weeks later there is NO brown algae in the tank, the plants are cleared, the rocks are 80% cleaned, and even the gravel in the area of the tank where I hadn't picked it out yet is showing reduced levels. Otos require clean water, so you'll have to take care of them, but they are truly amazing when it comes to certain kinds of algae. I wouldn't have believed it if I hadn't seen it.

The BBA isn't gone yet, and it's regrowing on the rock surfaces the Otos have cleaned (though interestingly not the driftwood or the dwarf sag), but it's better. The brown algae stopped, I've had a little bit of green spot algae on the glass. Nothing major, and I'm staying on top of it, but I traded one alae for another.

But I'm expecting this to take at least another couple months to dial it in. So I'll take progress provided by the cleanup crew and the extinction of the brown algae for now.

The last big improvement I'm trying to make now is dialing in the nutrient levels. As I mentioned above, getting the nutrient levels right and then dialing the light to where it needs to be makes sense to me. (I'm sure there are other ways to go about it.)

As I understand it the main nutrients are Nitrates, Phosphates, Potassium (macros), CO2 (it's own thing) and then trace elements (micros).

Because I'm moderately planted and interested in a stable tank that doesn't require weekly pruning, using full EI/ADA nutrient dosing seems like overkill. So I'm setting my macro levels on the low end of the range suggested by the 2HR Aquarist in this post: 6ppm NO3, 2ppm Phosphates and 6ppm Potassium, weekly. Along with micro nutrients via Flourish (as suggested on packaging). That's roughly 30% of the recommended macro dosage for the EI method (except Potassium, which is more in line with suggested levels). With Nitrates being low and Phosphates missing entirely in my tank right now, I think I probably have some room on the upside of those #s, but I wanted to start low and work up if things go well rather than jumping in high. My plants aren't dying, are all laying down deep roots, and some are growing, but there are yellowed tips and some pale leaves, the stem plants aren't growing very fast and etc -- there's some visual evidence (to my beginner's eye anyhow) that they are not thriving despite decent lighting.

The nutrient calculator at Rotala Butterfly has been extremely helpful in figuring out how to achieve those dosing levels.

I am not dosing CO2 separately yet. The CO2 calculator at Rotala Butterfly suggests my CO2 levels are currently between 35ppm and 60ppm. (My fish have never shown any sign of CO2 distress.) So even if those are artificially high readings due to a big hunk of driftwood, there should be plenty of CO2 available. I'm hoping I can stay on the "moderately planted" side of the line and that I don't have to introduce CO2. We'll see.

Finally, I've currently got my lighting set at the "Day Sim" time period suggested by Bentley Pascoe in this video. The intensities are all dialed back to 55% of his levels, just based on how the plants seem to respond to it so far. But once I've been dosing regularly for a few weeks I'll see how the tank responds and adjust accordingly. I really like the low-light periods in the morning and evening, and even with the long photo period the total time+intensity of the lighting is equivalent to about 4 hours of max light per day. Is that right? No idea! Once I know the plants have the full nutrients they need I'll tinker with it to see what works best.

As long as the cleanup crew can stay on top of the new algae and I keep the tank clean, I'm optimistic I'll get the plantscape where I want it to be over the next few months. I expect to learn a lot more as I roll this out though.

Hopefully this is helpful to someone else who has the same low level of planted knowledge I do. If not, nothing lost. It's a good record for me of what I was thinking today (and where I went wrong when things don't work!).

2,141 Posts
Congratulations on sticking through it!! Good little write up of an experience that MANY people go through when they start the hobby. Once you get through your first few algae blooms (believe me there's a 95% chance sometime along the line you'll have more) you'll start to not panic or get too bummed out when it starts showing up. You're spot on about tank and filter maintenance. Once you get your water change schedule and ferts dialed in you get an understanding of what is causing your algae, from that point it's just a matter of patience and water changes. Good luck on your new start!!

1,360 Posts
Excellent musing. Hopefully other newbies read this on their way through the new posts. Your experiences are insightful, humorous, and contain some good advice.

Have you considered starting a journal for this endeavor?

3 Posts
Discussion Starter · #4 ·
I think I will use this thread as a journal of sorts.

Update #1 -- I started adding macro ferts this week and the stem plants that hadn't really changed height much in the last couple weeks grew noticeably in like 4 days. Especially the bacopa caroliniana.

However, brown algae immediately reappeared on plant leaves and reemerged on the front glass as well. I'm leaving it for now since I have so many algae eaters, but I turned the light profile I'm using (see above) back to 45% of the intensity in the video (from 55%), and cut one hour of max intensity out of the peak.

I'm also confused about the CO2 levels in the tank. The online calculators suggest current levels of 35 to 80 (or higher) depending on whether I use the pH in the AM (~6.2/6.3) or PM (~6.6/6.7). I do use crushed coral in the filter and there's a hunk of driftwood in the tank, but I'm not sure how to account for those. The higher levels the calc spits out are confusing because my fish have never exhibited any distress and are healthy/long lived. Would love to understand this better if anyone has thoughts.

I'll post a current photo tomorrow after I tidy up.

1,249 Posts
For what it's worth, in my experience, crushed coral and co2 is a bad combo. I made the mistake of putting some in my filter when starting a new high tech tank once, and I could just never get the kind of healthy growth I thought I should be able to. Algae struggles taboot.

Then one day I was reading about calcium reactors and started to put two and two together... It was night and day once it took the coral out.

Every tank is different and your mileage may vary etc etc but I figured I'd mention it.
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