I've come across advice time and time again in these forums on "double-dosing a tank" with Flourish Excel to get rid of unwanted algae growth. So, in a last ditch attempt to get rid of remnants of green hair algae and some sneaky black beard algae that seemed to survive a 12 hour bleach dip, I broke down and went out and bought a bottle. Following the advice, I doubled the initial dose....

BAD IDEA

Mind you, the fish with scales do just fine, even at this ridiculous amount. But let me warn you - scaleless fish, including discus, will literally burn in this solution. I did a "test tank" the night before to see if there was any noticable differences and all seemed well and the red hair algae that was growing on the crypts wilted away... but the one fish I don't noramlly see, a syno featherfin catfish, passed soon after the dosing and I didn't even notice until after I did a whole day of water changes and "praying" to save my tank of discus who all started to go belly up within 15 minutes of the dosing.

So, we all learn by trial-and-error and live and learn. I just wanted to share my experience with you so you might avoid having the same thing happen to you.

Thanks for reading and always remember to take your time and move carefully when dealing with new chemicals/medications in your tanks. Keep an eye on your fish after a new chemical is added and do at least a 50% water change if/when you notice the fish are stressed out.

Thanks for telling us your experience. Hopefully others will learn from this.

I know others have been suggesting it but personally I wouldn't double dose with anything if the tank had fish in it.

I've done it a few time and it doesn't bother my discus at all. Only difference I notice is they all went crazy wanting to breed

Ron

We have just double dosed our tank but on strick advice from the lfs NOT to double dose that first dose... that one is already fairly strong, they also said from then on don't double dose every day, every 2 or 3 days should be fine, and we now have no black algae, i would highly recommend the stuff.

Hi Guys,

Just wanted to say "Really Sorry to hear about the loss of some of your Fishys" .

I use Flourish Excel, and have had excellent results with this, I will admit I don't double dose and I probably only dose every second or third day. I do wonder about the double dosing straight away, I would have thought you would at least have to build up to a double dose, rather than double dosing right from day 1.

Just a thought.

Lynda

My experience has been the same as Ronnie's

I double dose my tank and then add a second dose 2 days later and leave it for a week. all the Black Beard Algae dies and so does riccia and twisted val unfortunately

However my Discus, Kribs, Clown Loaches, Bolivian Rams, Bristlenose, Golden Bristlenose and Guppies show no signs of stress.

I don't do any water changes at all for at least a week and there is no carbon in the filter either.... Flourish Excel .... Just works for me... done it twice in the past year.

Guess it may work for some and not others. go figure :-?

Perhaps I should clarify. I doubled the initial dose. THAT was the bad idea. I'm sure that a double dose of the regular dosage (approx 1/4 of the inital dose) is just fine, but doubling the initial dose is the bad idea that I'm trying to help people avoid in the future.

Quick update, all discus have recovered aside from two that have a bit of damaged skin (will heal with time, I'm sure). All the green hair algae has turned red and is dying. Mind you, with the water changes and after everything that I did in the end this is the result of only a regular initial dose.

So Flourish Excel definitely works, just don't do the silly mistake I did!

yep.. that is what I have done... double the Initial dose... no problems and then another normal dose 2 days later

Really? What fish were in your tank(s) that you double-dosed? Any scale-less fish? Mind you, the other two tanks that I double dosed are perfectly fine (aside from the dead Syno) with only dead Riccia and twisted Val...

Thanks for sharing Blue, bit confused by your double the intial dose (approx 1/4 of initial) statement tho???????

so is the consensus to do a "normal dose" FIRST, then double it a few days later, double from the start, or just add another normal dose in a few days after initially just giving the tank a normal dose?

JoandWilly have you found the BBA comes back? Just curious because Excel is not cheap

No, i done the initial dose as written on the bottle, then doubled the dose's after that and done it every second day for 2 weeks, and that got rid of all the bba in the planted tank but our cichlid tanks used to be full of it and now its just disappeared from both of them so maybe hamilton water has a lot of phosphates or something and auckland water doesnt :-?

Have any of you double dosers actually used a control tank to see if it clears up with a normal dose of excel. Mine has cleared up considerably since i started adding normal rates. I have put it down to better plant growth leaving nothing for the bba to feed on. I also agree with Lynda that you should build up your dose if you are going to tip this into your tank with no heed to the manufacturers instructions

My initial dose was a double dose.

for fish I have in the tank see above posting. includes discus and clown loaches etc...

Thanks for sharing Blue, bit confused by your double the intial dose (approx 1/4 of initial) statement tho???????

so is the consensus to do a "normal dose" FIRST, then double it a few days later, double from the start, or just add another normal dose in a few days after initially just giving the tank a normal dose?

JoandWilly have you found the BBA comes back? Just curious because Excel is not cheap

BBA will be back if the water is not change regularly. no one can get rid of algae complete unless you want to rid off your plant.

the key word is control and balance.

i only double dose when my BBA got out of hand. (it is up to you.) i have no lose of fish for double dosing.

once double dose, i will keep the water for one week and change regularly for twice a week to rid of the dead algae.

once i am confident that it stablised, i will go back to once a week water changes.

Excel can be expensive but try to keep a good balance between lighting, fertiser and CO2 so that your plant is healthy enough to compete against the algae.

All the best.

Re phosphates in tap water in Hamilton I have had my suspicions for ages too because I always have a problem with hair algae (another reason to try some excel ). I'll call the council see if I can get a water report and then post the info.

Re phosphates in tap water in Hamilton I have had my suspicions for ages too because I always have a problem with hair algae (another reason to try some excel ). I'll call the council see if I can get a water report and then post the info.

Just get a phosphate test kit, it will easily show if there's any in the tap water. If it changes colour at all, there is too much...

Although, I have a new phosphate test kit, one of the Hagen ones. When I tried it out on a water sample to which I had added some KH2PO4, it still detected nothing when it should have been off the scale. It really makes me wonder about the usefulness of those things.

I have never used the test kits. Do they register for PO4 or HPO4 or both?

I just have to say that i find this all really frustrating! I have double dosed with Flourish excel to try to get rid of BBA and it has never worked!

I initially was using it for plant growth and when the BBA arrived i doubled and then even tripled dosed and nothing has made a difference. I have moved house, got rid of all the worst effected plants and have changed the substrate to something more nutrient rich. I was adding fertilizer to the water but do not plan to now i have a good substrate. Hopefully this will help combined with the right CO2 and lighting

I agree with Plantman, balance is the trick

Blue and Kim i am really sorry to hear about your fish, i love syno's especially.

BBA is the bane of my exsistance :evil:

I just have to say that i find this all really frustrating! I have double dosed with Flourish excel to try to get rid of BBA and it has never worked!

BBA is the bane of my exsistance :evil:

One thing i have found that BBA doesn't seem to like is current.

Added an internal filter into one of my tanks with BBA and in the line of flow all the BBA disappeared

Wow, I never gave my double dosing results. Well, I've been using the stuff for 3 months now and... it works!!! Yes, double the initial dose (which is 8x the standard dose in total) with a double standard dose 2 days later and leave the tank for a week with no water changes.

Keeping in mind the warning at the beginning of this post - watch your fish and do a 50% water change if things are looking crook - there's nothing more effective for knocking out algae.

Yes, it also kills off Twisted Val and Riccia, so if you value these plants remove them to another tank during treatment as the huge carbon dose WILL knock them out and they'll melt slowly and surely before your eyes.

Hey Blue,

I was about to email you about my riccias dying en-masse. Did'nt know flourish excel will kill them, and done a double dose because I bought some plants with BBA on them, my riccias have now all gone to riccia heaven.

CesarZ

Best to do preventive maintenance with new plants by giving them a soak in Potassium Permaganate before introducing them to the tank. Sorry your Riccia died, come on out for a visit and pick some more up.