BryceM

I know many of you have been following my 180g aquarium journal for a while now. The tank has been going strong for almost 30 months. Over the past six months it has developed some algae issues which were never present previously.

About six months ago I started to get a massive case of thread algae, especially in the upper 1/4 of the tank where the light was most intense. After a few weeks of messing around with this I started to notice BBA too - first on older Crinum leaves and then forming in individual balls down around the substrate. I checked my pH probe and found it wasn't working right. After replacing it (and therefore increasing CO2 levels) things got better and the aquarium was "happy" for three or four months.

For the past two months, I've again developed BBA, first as a minor nuisance, and more recently, a quite aggressive invasion. This did coincide with replacing my MH bulbs, which were quite old (2 years). IME, BBA is usually a sign of too little CO2. I've gradually lowered my pH controller to the point that it seems almost ridiculous.

For the first two years of the tank's existence, the pH controller was set to 5.95-6.15. GH has been steady at 4 and KH at 3 per Lamotte testing this whole time. I recently calibrated the KH kit and it was right on.

Over the past 6 months I've been gradually lowering the set-point of the controller. It's now down to 5.60-5.80. A 5dKH drop checker is yellow. Pearling is fine. The fish are definitely showing stress though. The congo tetras stick to the top 1 or 2 inches of the tank and the sidthimunki loaches become almost comatose during the CO2 period. Despite all of this, the BBA continues to get worse and I'm now seeing a resurgence of the thread algae.

Bioload is lower compared to a year ago. My choice in plants has gradually moved to more and more demanding species (toninas, R. macranda, etc.) so it is possible that the quantity of typical "rapid growers" is lower than at any other time. There are still several large stands of Bacopas, Limnophila, and other simple stemmies.

My upkeep routine has not changed. Apparent NO3, PO4, Ca, Mg, and KH levels are unchanged over the past year. 20% WC's are done three times a week with reconstituted RO. I add 1.5 ppm NO3 and 0.6 ppm PO4 three times per week. I'll admit these numbers are on the lean side, but I had no problems with that routine over many, many months. NO3 averages about 10 ppm and PO4 is between 1.0 and 1.5 on the Lamotte kits.

I'm unable to account for the need to push to ever-lower CO2 levels. For the sake of the fish, I clearly need to drop CO2 levels a bit.

There are a few possibilities:

- The pH controller isn't reading correctly, despite the fact that it calibrates to standards just fine.
- My fertilizing regime is off somewhere (insufficient macros, buildup of micros/Fe, or something else)
- There is an excessive buildup of debris, mulm, or other organic material in an ageing substrate.
- As life is getting busier, I am occasionally missing a WC or dose once in a while.

My plan at this point is to hit things with a week or two of high-dose Excel, remove all the affected plants, slightly increase my macro dosing, decrease the MH photoperiod by 30 minutes, and ease off slightly on the CO2.

Other ideas? Does anyone have experience with a similar, older, setup?

Bert H

While I don't have any direct proof, I would go with the idea of debris/mulm/etc build up on the substrate. Recently, my somewhat neglected 10 gal got a major clean-up and I ended up vaccumming all the substrate (Eco), which had quite a build up of stuff in it. Before this clean up, I was still doing my water changes/dosing regime but I could see bba, and some thread algae building. A couple of weeks ago, I did the large 'clean-up'. It's been like a different tank for the last 2 weeks. No trace of bba, and the little bit of thread algae that was forming has stopped and basically disappeared.

I know folks typically say not to gravel vac a planted tank, but I have always done some whenever I uproot/replant a particular area, so the whole tank gets it maybe once or twice during a year.

My 2 cents. I'm curious to see what others suggest.

Dan S

I agree with Bert, I did the same thing with my 40 gal. which also has (Eco), I thinned out a back corner that was packed with vals. and cleaned out (gravel vac.) the mulm and debris, after that, the little bit of bba and thread algae that I had has been reduced. All that debris just seems to add more nutrients for the algae! I hope this helps and you can provide us all with some updates, yours is one of my favorite threads to follow!

BryceM

I actually vac'd the right 1/2 of the tank about 2 months ago when I did a pretty major trim. I don't know if that changed anything but it did remove an unbelievable quantity of mulm. In any case, doing that for 1/2 of the tank didn't fix the problem.

Cavan Allen

Probably the second and third possibilities together.

It's likely a combination of increased mulm/organics and macro dosing that's too lean (that sounds a bit odd, but I believe it's true). You shouldn't have to have the co2 that high.

BryceM

So, I've doubled my KNO3 and KH2PO4 dosing and turned down the pH controller a bit. So far, the fish seem quite a bit happier.

I've removed about half of of the affected foliage, being limited in my efforts by time constraints. Sadly, my large mature Crinum calamistratum was too badly affected to salvage. It had just flowered again too. OTOH, it had again produced three fairly large daughter plants which I was able to save.

There's still a fair bit of thread algae in the upper portions of the stemmies, but overall, I'd say the plants are looking better. BBA is still far too prevalent, especially in lower regions around the substrate.

When I carefully examined the plants, many of them showed signs of N deficiency, especially in their lower regions which had melted away in some instances. I can only assume that over time I had managed to lean my macro dosing to the point of sustainability, but just barely so. I probably got lazy for a few days and forgot to dose. As I recall, this coincided with a rather large trim (which took more than 6 hours) which opened up extra light to previously shaded areas. There was probably an uptick in N consumption precisely when I had neglected to keep up on macro dosing. If all of this does indeed prove to be the point, at least I will have established the actual N and P needs of the tank, which is certainly something worth knowing.

I added 75 ml of Flourish Excel today. I'll do this for a few days and watch the BBA for signs of turning pink. My intent here is to try to speed the recovery along. The real key will be getting back to a more stable condition for the long run. Yes, it's a form of cheating, but manual removal of thread and BBA in a monster tank of this size simply requires more diligence and effort than I have time for at the moment. I don't really suppose that adding a bit more of the macros will have any downside. It's still quite lean compared to what many people are doing. If I keep to the current schedule, I'll still only be adding 9 ppm of NO3 and 3 ppm of PO4 per week.

When I get a few minutes, I plan to vacuum out the left half of the tank. That chore might have to wait for the weekend.

JERP

Sometimes in a real dense tank, you can have cold spots, or even anaerobic spots in the aquarium.

I once stuck my fingers into a 1" thick layer of mulm at the back of my tank and it was freezing cold. It smelled sulfurous when I removed it. I thinned out the plants so water current gets through and sucked out the mulm and the algae in the tank dropped considerably. My stem plants were much healthier as well, there was no stem rot after I started doing that. I've found that water flow has much more to do with keeping the lower portion of a stem plant healthy than access to light.

Do you have a glass lid? Clean it regularly. The deposits from condensation can cut down a lot of light.

You can kick up a tremendous amount of garbage (organics) into the water when you gravel vac. I try not to touch the gravel with the vac. I just skim what's on the top. When I do a deep gravel vac, I do a second big water change the next day.

There's something else I'm missing but can't think of it now.

1aqumfish

Check your filters and water flow, hoses over time become clogged I have found some gravel in a filter disconnect that stopped a mag 350's flow causing problems. Nutrients, light and water movement all effect algae.

BryceM

Nope, no glass lid thankfully. It's a partially enclosed open top and the lights are up 10-12" from the water.

The filters are fine. They get regularly changed every 3 months. The closed-loop system might be another story. I probably need to disassemble it for a good cleaning. Ugggh. That's a chore that I've been putting off. Maybe I'll just get one of those brushes on a long wire. I'll still have to take down the CO2 reactor though.

Zapins

The same thing happened in my 55g that has been set up for 5 or 6 years now. Around the 3 to 4 year mark I had awful BBA and thread algae (but the BBA was just horrific). I also gunned my CO2 until the water bubbled like soda (after removing the fish). The pH was 4.8 or so constantly and it didn't seem to improve things.

I think it was mulm build up that was accumulating in my huge java fern mats (80% of the tank was planted with java fern on the wood). So I ripped it all out and cleaned the tank. I planted anubias nana petite instead since it is easier to clean and the algae problems have gone away.

I wonder if this is a common problem with old tanks? Usually I don't think people keep the same design set up for more than a year or two from what I have seen.