fertilizer and fish deaths?

Wat2Go

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Feb 23, 2007
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Because our plants weren't doing great I'd thought to add a little bit of fertilizer to see if it would make any difference. I bought the API Leaf Zone Aquarium Fertilizer (Petsmart) and added the required amount (cap full per 60gallons, once or twice a week). Added it twice this week and this morning three fish had died! (Male high fin swordtail, a spotted cory and a lyretail molly). The tank is 110 gallons long, parameters are fine (amonia o, nitrite 0 , nitrate about 20). I am doing water changes once a week (about 40%) and haven't had any fish dying in a long long time.
Could it be the ferts?

L.
 
I think they are suppose to be added after a WC...? More as needed in a heavily planted tank. Not 100% on this though
 
You had not overdosed - I use the same ferts and it says to dose at a capful (10 ml) per 20 gallons, (I use 5ml for my planted 10g and have had no losses). I wonder why your plants were doing badly - did this mean that there were pieces of rotting plant in the tank? It may be that this had caused toxins to rise and the rotting plants might have contributed to the fish deaths. Were you keeping an eye on ammonia/nitrates etc?
 
I think they are suppose to be added after a WC...? More as needed in a heavily planted tank. Not 100% on this though

According to the label, you just dose the tank once a week. If you are doing more frequent water changes, you might dose the water you are adding, but personally I just stick to a routine of weekly feeding with the fert and it works well.
 
Plants not doing well: Corkscrew wasn't growing, amazon swords had a few brown leaves (that I removed immediately), hornwort looked sad, moneywort slowly dying...So I changed light bulbs and added the ferts.
Yes, I did keep an eye on the amonia, nitrite and nitrate, all fine. First time I added ferts after wc, second time I just put it in.
I will add more plants this week (java moss and pellia)...

So, I'll just assume it was one of those things and not really the ferts.
No losses today, all fish seem happy!

L.
 
That's good news. Is your light level okay? Remember some plants want a lot of light to grow. I am using standard compact flourescents, 2 x 13w units in a 10 gallon, which is the equivalent of about 120 watts incandescent. My new planted tank looks bright, but it's not considered brightly lit by plant growing standards. Lighting calculations are not hard to do and are available all over the place, including on this site in the plant section, but with 100 gallons, unless you originally set it up to cope with the demands of the plants, you might well need stronger lighting. That might be the problem. Good luck with the new fish.
 
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