How much salt to "dissolve" freshwater algae

[Little Fish]

I have a freshwater tank with F8s turning into brackish. When cycling in "freshwater mode", I introduced all sort of algae into the tank. I learned my lessons of introducing plants from a less than reputable store into a tank without bleaching Since then I have been using a SAE, a Flying Fox, and 2 Gold Barbs to keep the algae at bay. However, I have to return them to the store (not the same where I got the plants) when I put F8s in the tank and start putting salt. The algae came back with a vengeance even with phosphate & silica absorbing material in my filter. Does anyone know how much salt can freshwater algae tolerate before they die out? Or can they thrive in brackish water? My tank is currently at SG 1.002 and I'm raising it slowly with weekly water changes to SG 1.008.

 

[andywg]

I would be a little careful with an SG up to 1.008 with Fig 8s. Most of what I have read indicates you are better off keeping them to around 1.005 (but I am open to correction on this).

I'm not too sure on the algae, have you identified what is causing it, for while the FW algae may die in the salt, there are plenty of brackish and marine algae to replace it.

 

[Little Fish]

Yes, it seems like SG 1.008 is the high limit for F8s. May be I'll stop between SG 1.005 and SG 1.006 just in case.

I think I'm partially responsible for the algae boom and I also suspect a high level of phosphate in my water supply. I have an open tank with Red Mangroves. Some of them is not tall enough to have leaves above the water level that I want it to be. I added plant growth supplements and run a 65W Actinic 8 hours a day with a 65W 10,000K 6 hours a day overlapping. The Red Mangroves start to grow very well. Even the ones that lost all the leaves during shipping start to bud. I stop adding plant growth supplement 3 weeks ago. However, I did not shorten the hours for the lights because some of the Red Mangroves are still too short. I'm hoping as the salinity increases the algae will die.

You bought out one interesting point about algae in brackish water. Since the tank was FW and the F8s were kept in FW in the fish store, there should not be any brackish algae spores (if algae really propagate with spores). If the FW algae die out because of the salt content in the tank, there should not be anything left then. Or is it possible the brackish algae do not show themselves until the condition is right? Or some of the FW algae will adapt to survive in brackish water?

 

[andywg]

I don't think spores are the cause of all algae or else it would not appear in marine tanks.

Get a phosphate tester and some Phosban or Phoszorb. That should help. Also, once the SG starts to hit 1.006 and above then Protein Skimmers become more effective at removing nutrients from the water.

If the mangroves are a too short to have leaves above water, try putting them onto a polystyrene bedding tray so that they float at the right level, then once they have grown enough, remove the tray.

I think that some algae probably can survive brackish and fresh and there's probably more than enough bracksih to replace any freshwater that can't survive the transition.

10,000K is a little high temperature wise for plant growth. Ideally you want between 5500 and 7500 to promote ideal plant growth.

HIH

Andy

 

[Little Fish]

I already replaced the activated carbon pack with a Phos Zorb pack in my canister filter. I have a Seaclone 100 standing by but I like the look of plants in the tank. Besides, the Seaclone is not particularly effective comparing with some other better skimmers. The price was right though. The F8s kind of like plants in the tank too (so they can munch on them ).

At this moment, only 2 of the mangroves are too short. Nonetheless, I will feel bad if I "drown" them. At the current growth rate, they should be able to reach the height I want in about 3 weeks. Good advise on using styrofoam floaters but the mangroves already took root. It's tough to remove just the 2 without pulling entangled roots of the neighbors (I tried).

Yes, I agree on the lighting requirement. My other freshwater tank is running a single 65W 6700K lamp. The Actinic lamp for the brackish tank most likely is not doing much at this moment except for show and the 10000K is not ideal. The reason for this setup was; originally the brackish tank was going to be set up as a reef tank. However, I fell in love with the F8s once I saw them in the fish store. So I ditched the idea of the reef tank. I wasted money on some of the equipment that I won't use for the brackish tank (wave maker & pumps, fluidized sandbed filter, protein skimmer, extra canister filter, etc) but I think I might have saved more money for not running a more expensive reef tank.

 

[CFC]

Why not stick the wave maker and pumps on the brackish tank? Brackish areas are usually affected by tidal changes so to recreate that i would have them set up on timers to come on for a couple of hours every 12 hours, if you want you could even position pumps at both ends of the tank and have the timers set to do the tide coming in for the first hours and then the tide going out for the second. It would certainly make aquarium life more interesting for the fish.

 

[andywg]

CFC's right, a tank that immitates the tides would be perfect. Most of the reef equipment can be used well. The extra cannister and fluidised sand bed could help a lot with your woes.

The extra filter will ensure the water is clean (as most pouffers require very high water quality) and if you took the sand out of the fluisised sand bed chamber and replaced it with some phoszorb/ban then it should improve its ability to remove the phosphates from the water.

You could also try cutting the photoperiod of the 10k bulb down a bit too to prevent too much light that isn't wanted by the plants (like only have it on when you will be viewing the tank).

HIH

Andy

 

[Little Fish]

Why not stick the wave maker and pumps on the brackish tank? Brackish areas are usually affected by tidal changes so to recreate that i would have them set up on timers to come on for a couple of hours every 12 hours, if you want you could even position pumps at both ends of the tank and have the timers set to do the tide coming in for the first hours and then the tide going out for the second. It would certainly make aquarium life more interesting for the fish.

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Great suggestions! I only thought of wave makers generate waves and never thought of simulating the tide with it. I was running 2 pumps on each side of the tank alternate in short period of time to simulate waves. I guess it would be ok if I had life rocks and corals that needed strong current and the life rocks would absorb/block some of the current. However, when I changed my mind and cycled the tank with freshwater, the current was way too strong and direction changes were too sudden for the Gold Barbs (used for cycling) in my small 29G tank. I removed 3 pumps and set the last one to constant on since then.

I will put one of the pumps back on the opposite side. What times do you suggest I run the pumps? May be 4am to run the left pump for an hour, 5am to run the right pump for an hour? Repeat the same sequence at 4pm? Is this what you meant?

 

[andywg]

I would have the one on the left on for a a couple of hours or so at say 6-8am and then the one on the right on from 6-8pm. That should represent the tide going one way in the morning and another in the evening.

 

[Little Fish]

CFC's right, a tank that immitates the tides would be perfect. Most of the reef equipment can be used well. The extra cannister and fluidised sand bed could help a lot with your woes.

The extra filter will ensure the water is clean (as most pouffers require very high water quality) and if you took the sand out of the fluisised sand bed chamber and replaced it with some phoszorb/ban then it should improve its ability to remove the phosphates from the water.

You could also try cutting the photoperiod of the 10k bulb down a bit too to prevent too much light that isn't wanted by the plants (like only have it on when you will be viewing the tank).

HIH

Andy

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I think you are absolutely right about using the fluidized filter with Phos Zorb. It should greatly improve the phosphate absorbing efficiency. However, the Rainbow Lifegard I have is a pain to restart, at least the way I run it. I did not connect it inline with my canister filter because I wanted the canister filter to run at full strength. With the canister running at full strength the fluidized sand would get out of the fluidized filter and into the tank. I was test running it in my 46G freshwater tank and I had to use a separate powerhead so I can adjust the fluidizing level. The pain came in with I had to shut it down. Since it wasn't connected to a canister filter, the intake pressure would drop when the water flow stopped. The sand in the main chamber backed up into the center intake chamber. The powerhead did not have enough power to push the sand back into the main chamber. Shaking the filter did not help either because the sand already filled half the intake chamber. The only way I found to restart the filter was to take the whole filter out and connect the intake to the laundry room facet. I turned the facet on gradually until the fluidize action restarted. Then I ran as fast as I could and reconnected the whole setup before the sand settled again. It was kind of stupid but I could not find another way that would work.

I think I would definitely shorten the period in 3 weeks.

 

[andywg]

Try connecting a larger powerhead to the fluidising chamber but put a ball valve in line so that you can use it on full bore to get the media (sand or phosban) moving and then turn it down so that the media is not washed out.

If it means turning the pump down quite a bit then put a T-joint in the line with a ball joint on each of the two exits with one going to the filter and one going to the tank so that the powerhead can return the rest to the tank and it will prevent excess strain on the powerhead from constantly pushing against the valve.

 

[Little Fish]

There is so much I need to learn about aquarium plumbing. The T-joint is a great idea to relieve back pressure and prolong the life of a powerhead.

There is an output adjustment value on the fluidized filter to limit the flow if I want to take the easy way out. Nonetheless, I'm shy of buying yet another more power powerhead. It's getting kind of expensive.

 

[Little Fish]

Just finished raising the SG of my brackish tank to the target of 1.006. I started the nitrogen cycle in freshwater mode and have plants infested with all kinds of algae in the tank. This gave me the (unintended) opportunity to observe how different kinds of algae strive in different salinity. At and below 1.002, the fuzzy type that sticks to the plants and glass dominated the tank. At 1.003 hair algae took over and formed long strings on the mangrove pods despite weekly cleaning. At 1.004 hair algae stopped growing and the new green slimmy algae covered every inch of the bottom like a thick carpet. At 1.005 the algae that formed the carpet became much thinner but did not go away altogether. It is still the dominate type in the tank at this moment with a SG of 1.006. The hair algae ceased growing but does not disappear unless manually removed and the fuzzy type shows minor growth. It will be interesting to see if all the algae would die if I keep increasing the SG. However, I think I have already reached the best salinity for my F8s and I have to stop. In summary, it seems like all freshwater algae will survive in light brackish if the SG is raised gradually.