Algae explosion after new light

[realgwyneth]

Hi again,

I recently splurged on a fancy Fluval AquaSky 27 watt light to replace an old light hood that was getting dimmer by the day. Wow, I can see my plants and fish now! But now, 3 weeks or so later, I can also see my anubias is just covered with dark algae of some sort I've never had before. It's hard to get it off the leaves, even with a soft toothbrush. I keep turning the light level down (and making "sunrise" and "sunset" periods longer), but the algae is getting worse. (Pictures below, I hope). I've got a total of about 8 hours now, including lengthy sunrise and sunset time with the white, red, and green light at 70% and the blue light at 10%.

It's a well-established 65-gallon tank with a good amount of plants, mostly anubias and java fern. There's also a lot of java moss. Current occupants include 1 kribensis, 3 Schwartz corys (want more!), 10ish cherry barbs, 7 red eye tetras, and 1 ancient ghost shrimp left over from a group. (I'm planning to add 3 more corys, a few more cherry barbs, and to replace the red eye tetras with ... something more interesting ... as they age out.) The tank has been running for several years, and the only thing that's really changed in the last two years is the light.

pH = 7 - 7.5
ammonia = 0
nitrites = 0
nitrates ~ 10 - 20
tap water source is quite hard, but there's a huge log to soften naturally.
25% WC weekly
Capful of Flourish weekly

Should I keep reducing the light level or time? Should I add more plants to consume nutrients now that I have better light? Should I stop fertilizing? Will amano shrimp eat this brown algae or will my female krib eat the amano? She doesn't bother the ghost shrimp, but he was bigger than her when she came into the tank. Can you even find amano shrimp in Texas? Is there some other fish (in small quantities) that would do a better job of eating this stuff on the anubias? I'm not sure I want a plec@. Insight greatly appreciated!

 

[Byron]

The algae is a form of black brush, it has more than one form. Anubias is very susceptible to this algae under bright light. Other plants will be too. Nothing suited to this tank will eat this algae, the only way to deal with it is to establish the light/nutrient balance.

Floating plants will greatly help. Substantial floaters, like Water Sprite, Frogbit, Water Lettuce.

I assume you cannot control the intensity. But duration is controllable. You can reduce the period of the brightest light (the "day" to the fish and plants) down to six hours. Keep the dawn and dusk periods short, as they will be used by this algae. Daylight entering through windows is also a factor; I used to see black brush algae increase in summer due to the longer and brighter days, until I blacked out the windows. That was in a dedicated fish room, it may not be so easy in a living room but you can work around it.

If I could see a photo of the entire tank to assess the plant species/number I might be able to suggest changes in the fertilizer. Obviously any added nutrients that are not needed by plants will encourage algae. Floating plants however will use a lot of these, so another benefit.

On the hardness, what is the GH? And the KH of the source water if you know it?

 

[realgwyneth]

Thanks for the feedback, Byron!

I'll attach a photo of the whole tank below. I can control the intensity of the light; it is currently at 70% for white, 70% red, 70% green, and 10% blue, but I can lower it. I've actually lowered it from 90% to 70% over the last two weeks (10%/week) as well as altering the sunrise/sunset intervals. I've reduced the total lighting hours from 10 to 8 over two weeks as well. It sounds like you're saying I should maybe not use the sunrise/sunset intervals at all?

The last time I tested the tank, I got GH of 60 ppm and KH of 40 ppm. As you can see, maybe, in the photo, there is a huge piece of driftwood (it's covered with java moss so maybe not), which helps soften the water.

I'm told our tap water is "liquid rock," but I'm having trouble finding a water report listing actual KH for Austin, TX. This document (https://www.austinutilities.com/assetmanager/downloads/documents/pdf/WaterQualityReport.pdf) says "water hardness" is 16 grains per gallon. It looks like that works out to 275 ppm?

I'd actually like to add some more plants, but up until I got the new light, I just couldn't grow anything except anubias and java fern/moss. Maybe now I can try for more diverse plantings and floating plants.

 

[realgwyneth]

Also, it may be hard to tell but there are two HOB filters on this tank, which might preclude some types of floating plants?

 

[Byron]

You have all low-light requiring plants, and correspondingly low nutrient requiring; this means the more intense the light, the more problem algae. The floating plants will help. This is more important than filters, and on that note, you do not need two filters. What is the tank size (dimensions and volume)? In any event, the plants I suggested are substantial and once they start spreading, they will (if allowed) cover the surface and not be hampered by the filter(s).

As for the duration, you can reduce it an hour at a time and leave it for a couple weeks to see the effect. However, the floating plants will factor in to this, as will reducing the intensity. This is difficult for me to assess from a photograph. Different lower plants plus the floating plants might allow you to leave the intensity higher. As for the dawn/dusk issue, I would not have these more than 30 minutes each. This feature is useful to avoid a sudden on/off of the light which harms fish. I always used daylight to achieve this, meaning the tank light came on and went off while the room was in daylight. But you can work out the scale according to when you have the tank lighting on for viewing. As long as it is the same every day, which it would be.

As for the GH/KH. GH is 60ppm [= 3 dH] which is very soft water. The GH is fine for the fish and sufficient for the plants. The KH is 40ppm [= 2 dKH] which is not going to do much pH buffering, so expect the pH to lower as the tank biological system establishes (not a problem with these fish or any plants). Can you post the GH and KH of the tap water, curious if it is different.

 

[realgwyneth]

Thanks for the insight, Byron! I'm reducing the light time again (7 hours) and shortening the sunrise and sunset intervals to 30 minutes each. We also added some new plants (moneywort and wisteria) and something that floats (frogbit?). The second filter is overkill but after we went through a spate of power failures where the filter wouldn't come back online without being completely broken down, we just added a 2nd filter as insurance. I'm out of full test kit for now so I can't test the tap water. I just keep a nitrate kit on hand since everything else is (has been) so stable). The LFS also suggested we try a round or two of PhosGuard. So we've put all this in motion and will reevaluate in a week. I've been wanting to try higher light plants for awhile now, so now I have reason to justify the purchase, right?! I realize that I may have complicated things a bit with the new variety of plants ... but I should probably not change anything else for a week to see if it's working.

 

[Byron]

Thanks for the insight, Byron! I'm reducing the light time again (7 hours) and shortening the sunrise and sunset intervals to 30 minutes each. We also added some new plants (moneywort and wisteria) and something that floats (frogbit?). The second filter is overkill but after we went through a spate of power failures where the filter wouldn't come back online without being completely broken down, we just added a 2nd filter as insurance. I'm out of full test kit for now so I can't test the tap water. I just keep a nitrate kit on hand since everything else is (has been) so stable). The LFS also suggested we try a round or two of PhosGuard. So we've put all this in motion and will reevaluate in a week. I've been wanting to try higher light plants for awhile now, so now I have reason to justify the purchase, right?! I realize that I may have complicated things a bit with the new variety of plants ... but I should probably not change anything else for a week to see if it's working.

Why would you think you need phosguard? This is another risk.

 

[realgwyneth]

Uh oh. Why is this another risk?

 

[Byron]

Uh oh. Why is this another risk?

The fewer the additives/substances the better for the fish. There normally would not be a phosphate issue. Phosphate is a plant nutrient, and there is enough in fish foods to provide this. Removing it should not be necessary. Back to my question, why on earth would a fish store think phosguard beneficial?

 

[itiwhetu]

The higher the oxygen content in the tank the less algae you will have, a lower temperature can help and also an air curtain can be beneficial in lifting the oxygen content of your system. The more plants you have in your tank the less algae you will get.

 

[AdoraBelle Dearheart]

Off-topic, I'm no help here I'm afraid - just wanted to say that those cories are gorgeous!! You should definitely get some more and try to spawn them

 

[realgwyneth]

The fewer the additives/substances the better for the fish. There normally would not be a phosphate issue. Phosphate is a plant nutrient, and there is enough in fish foods to provide this. Removing it should not be necessary. Back to my question, why on earth would a fish store think phosguard beneficial?

OK, that makes sense. I'll take it out (it's just a pouch that goes in the HOB filter). I don't know why the LFS person suggested it, as it was DH having that part of the conversation.

 

[realgwyneth]

The higher the oxygen content in the tank the less algae you will have, a lower temperature can help and also an air curtain can be beneficial in lifting the oxygen content of your system. The more plants you have in your tank the less algae you will get.

Thanks, we're working on adding new plants ... that was the reason for getting a better light in the first place. Alas, we can't lower the temperature of the tank below about 77, the same as the inside of the house. (It's gotten over 100 (F) here almost every day since mid May, and that's the best the AC seems to do.) I'll go look into how I could add some more bubbles.

 

[realgwyneth]

Off-topic, I'm no help here I'm afraid - just wanted to say that those cories are gorgeous!! You should definitely get some more and try to spawn them

Thanks! They have definitely become everyone's favorites. As soon as the weather cools down some, we plan to add more, but it's too hot to transport fish right now.

 

[AdoraBelle Dearheart]

Thanks! They have definitely become everyone's favorites. As soon as the weather cools down some, we plan to add more, but it's too hot to transport fish right now.

Oh for sure, I'm going to trading some fish with a local hobbyist soon but even here, it's too hot at the moment to be transporting fish so we're waiting until it's cooler. Can't imagine how hot it is there!
I can see why the cories rapidly became favourites. Corys are one of my favourites too, but these are something special altogether. Really lovely species.