I love the community here. You all have proven to be an invaluable source of information and advice to a great many people who enjoy this hobby, and itís as good a time as any to say thank you to all who participate. I always enjoyed reading this community's discussions, but have never had much cause or inspiration to post until now. Now however, I would be immensely grateful for any and all input regarding a project I am now taking on.
In essence, I have volunteered to make changes or reset a large planted aquarium tank in the lobby of a small shipping company that is not faring well. This tank has proven to be a mixed blessing for its owners and the person managing it previously. It has experienced a slew of problems over the years, not the least of which is that it was re-purposed from being a tropical reef tank about a decade ago. Because this tank was managed by a professional company, I have access to a good record of work done on the tank and have been able to piece together a lot of the historical data for this tank. It has been re-planted/scaped many times over the years to greater or lesser degrees of success. It was last re-planted and aqua-scaped about 4 months ago, and the system in general has failed to thrive, and I've been asked to help. I have a couple of questions for you all on particulars I have not been able to secure myself.
Just a quick note about the pictures and algae: this was about 2 days after the initially requested thorough cleaning of the tank where I attempted to manually remove all I could, so it looks less severe than it really is.
The tank's setup is large, complicated and convoluted and it would take some time and space to explain it all. However, I can answer any questions, and I will try to explain further if you think it would help you answer a question. In short, it's a 160 gallon tank with a 120 gallons of sump water. It has two external mag-drive pumps returning water from the sump, one directly to the tank, one to a series of in-line equipment. In order, a 20 micron pleated cartridge filter, a chemical filtration chamber containing activated carbon and Seachem Phosguard, and a large UV sterilizer. Water leaves the tank from two weir boxes before returning to the sump. Co2 injection is sent to a ceramic diffuser disc wedged under the intake for the filtration loop. Light is OK, its a 250W metal halide and some HO fluorescents that have about 50 PAR at substrate on the edges, with about 100 in the center. It also has a diatomaceous earth filter runnning in the sump.
The dosing regimen for a long time has been set at the following
- 50 mLs flourish potassium added 3 times a week.
- 15 mLs API algaefix added twice a week.
- 10 mLs Flourish iron added once a month.
- In-substrate fertilizer sticks added every 6-8 months.
I've made some obvious changes like a reduction in photoperiod, more water changes, more filtration cleaning and otherwise giving attention to the system. But there are a few major points I'm not positive about that I'm soliciting advice on. Like I said, if you think you can answer any of these questions I would most appreciate it!
A: dosing advice? I've never managed a planted tank with this many gallons before, so I'm rapidly trying to get up to speech on fertilizing regimes.
B: Are the above pictures cyanobacteria/BGA like I suspect? What is spreading on the leaves, especially at the edges of the tank in pics 2 and 3, looks very BGA-esque to me. If this is cyano, it has a pretty good foothold in the tank and substrate and I may be researching treatment options, such as dosing erythromycin to try to catch up for such a long time of neglect. Any input regarding battling BGA is welcome if true.
C: Stop the algaefix? I've never dosed this chemical in a tank with such regularity, and I cannot find a firm answer in my research about the interaction with carbon. I suspect the carbon is absorbing it just because the tank gets 4 doses between water changes and it would probably have killed fish if not, but I'm not positive.
D: Kibosh the phosguard? Water quality data shows a long history of phosphate numbers < 1 ppm, so Iím concerned that the phosguard is stripping all of the phosphates from the system and contributing to an environmental parameter favoring algae growth.
Any other advice or discussion is welcome of course. Thanks for reading!