Thoughts on an awkward tank rebuild...?

[DrNic]

I've been fighting black beard algae in my 75G tank for a while now (see previous posts) and I'm rather certain the problem stems from the river stone gravel in the tank which propagates the algae due to water chemistry issues (long story). As a result sometime in the next few weeks I'm going to a complete rebuild of the tank. But I have some concerns.

My plan is to bucket the fish, completely drain the tank, remove ALL the decor, plants and gravel. Rinse out the tank and canister filter/tubing with some vinegar to help kill any algae spores and pull off all the algae by hand if necessary. The filter media itself (which seems to be free of algae), will get rinsed in tap water but not vinegar as to help keep at least some of the bacteria alive. I'll then add fresh gravel (aquariumplants.com soft belly soil), plants and driftwood then refill the tank, rebuild the filter and get the system running.

My problem is how do I get the fish back into the tank without shocking them since I'm rather certain the water chemistry will be different. I don't want to risk adding the bucketed water back into the tank and recontaminating the tank with algae. I'm tempted to net the fish and simply drop them in but I worry that may shock them too much. A friend suggested filling a bucket with 50% new and 50% old water and transfer them into that for a while, then net them and drop them into the new tank.

I'm also a little concerned about the cycle status of the tank after such a large rebuild/cleaning. I'm going to try to preserve the filter media as best I can but even then I'm worried about algae coming across on the filter media.

Aside from a few buckets, I don't have the space to temporarly house these fish long term in another tank either. (I haven't convinced my wife to let me get a second 75G yet )

Any thoughts/suggestions would be great.

[Cermet]

You can, while cleaning the old tank, add a little new water to the storage bucket every twenty minutes; by the time you are done, they will be mostly adjusted. Don't forget an air stone in the bucket! A heater many not be needed since the weather is warm.

[Cliff]

Do you have a QT tank you could keep them in for about 2 to 3 weeks?

You could use the already cycled filter media from the existing tank in your QT set-up filter. This would allow you to do a fishless cycle in your existing tank before moving the fish back in.

I'm not too sure if this is a option for you but I thought I would mention it anyways

[CrunchyLeaf]

Will it get rid of the algae if you use the old filter media again? or conversely, won't rinsing it in tap water cause you to have to cycle again anyway?

I know you said you don't have a place to keep them long term, but when you're putting so much time and effort into something I would hate to see your problem just come right back.

Perhaps see if you can find a cheap 20 gallon tank that you could use temporarily while you do a fishless cycle on the 75gal? It doesn't have to be anything fancy, just the $20 craigslist special.

[ryann]

Rinsing your filter media in tap water will most likely kill your bacteria on the media. Use dechlorinated water to rinse it or the bacteria will be killed by the chlorine. As long as you keep the media in dechlorinated water you should be able to keep the bacteria alive.

I agree with adding new water slowly to buckets with the fish in over the course of the day and then using a net to put them back in the tank.

You might have a mini cycle but I think you should be able to avoid a full cycle again.

[DrNic]

@Cermet, That's a good idea I might try that.

@Cliff, Unfortunately the fish would need at least a 55G quarantine tank and i don't have any spares at the moment. I agree that would be the best solution though since it would allow me to totally clean/dry my filter media and start over.

@CrunchyLeaf and ryann, I should have been more specific. The water will be dechlorinated, just not the algae-infested tank water. I'm trying to remove as many of the spores as possible. Once I get the substrate removed I suspect the algae will die off. It's a long story but in short, the substrate causes my KH and pH to drop, so I currently have a bag of coral in the filter which increases the KH and brings the pH back to 7. This is actually what this type of algae thrives on. Hopefully, once I get the new substrate in I'll be able to pull the coral out and without that source of carbonate, and perhaps the addition of some CO2 the algae will disappear.

[Surfdog]

This may be a dumb question, but here goes anyways. Is there nothing that can be added to the tank to kill off the algae without harming the fish or cycle? Something like red slime remover we have for SW?

[DrNic]

In theory Fourish Excel (a fert) and/or CO2 can be used to kill the algae. I've tried both. Excel didn't do much and I used a high enough dose that the fish started acting odd. I'm running CO2 in the tank now which helps keep it at bay but doesn't 'clear' the problem since this algae doesn't really get eaten by anything well so even if it's dead it just lingers.

This particular type of algae can be a beast to get rid of. Once it gets in your tank it can linger for a LONG time. I've known pros who have given up on tanks completely after dealing with this stuff.

At the moment the plants and decor are covered with the stuff which is why I'm planning on starting over completely. Remove as much of it from the tank as I can then continue to run CO2 in the tank to help remove any remaining algae once the setup is running 'fresh'.

[dizzydezzy]

who do you have living in the tank? Any chance you could maybe borrow a siamese algae eater from somewhere (or get one permanently?). Mine loves the beard algae like it's candy, took him about a week to completely de-beard a 45 gallon..

[DrNic]

The tank currently has goldfish and some large syno cats. I've thought about getting an SAE, but I'd rather just fix the water chemistry problems anyway. If it comes back in the new setup I'll probably get one or two though.