Fish Die-Off In Established Fresh Water Tank

[miksan]

I have a year+ old 40g South American planted Uniquarium (see http/www.advanceaquatanks.com/). The filtration system is self contained. Turnover on the tank is approximately ten times per hour. The water is titrate tested, using an API Freshwater Master Test Kit, at least twice per week. 4-5 gallon water changes are made once every two weeks. I recently replace my year-old Marineland Reef Capable LED Aquarium Lighting System with a Marineland 24-Inch to 36-Inch Aquatic Plant LED Light with Timer (Reef Capable 10k light was burning out my plants within two-three weeks).

This is a South Ameican dwarf Cichlid tank (Varies 4-6 Bolivian Rams, 8-12 neon tetras, 4-6 otocinclus, 3 small cory cats (e.g. false juli). Water consistantly tests great: pH ~6.4-6.6; Nitrate, Nitrite, Ammonia is zero. Plants are planted in a natural Caribsea Floramax substate, which varies from 0-1.5 inches in depth; there is also some fine white caribsea sand for the dwarfs - There is no undergravel filter. The bubbler ariator was originally removed to promote plant growth - with my current problem, I am considering putting the ariator on a timer and running it only during night hours (when plants consume oxygen).

My problem is that whenever gravel is cleaned and a water change is made, I get a fish kill - not all, and not species specific either. I have been in the aquarium hobby for forty years and have come full circle from SA to African Rift to growing Reef coral back to SA - only now with plants. Plants used are always live-aquatic/snail free specimiens. My thoughts are that there is a severe oxygen depletion and the night-time arriation seems locical, but it is only being implemented providing the immediate arriation addition fixes this problem.

If there are any other experienced imput it is welcome - With all due respect, please submit nothing in the newbie category that is not already covered above. And again, thanks in advance.

 

[phoenixgsd]

im curious why you have no nitrate, did you really shake both bottles?

 

[miksan]

Thanks for your response.

In case you're not familiar with the test kit specified, the test is a two part titrate of ten drops each in a 5ml sample - Yes, shaken

Within the parameters of the test kit - The water's nitrate is very close to zero. Nitrate, which is waterborne and not is the Caribsea medium (feeding the plants), is passed through a nitrate removal medium.

 

[leighton_87]

I'd have to agree with the above - API kits are famous for giving false nil readings if bottle 2 isn't shaken vigorously (many resort to hitting it off hard surfaces to make sure it's shaken enough).

Unless the tank is very understocked and very heavily planted I cannot imagine a situation with anywhere near nil nitrates with fortnightly 10-15% water changes

EDIT - you hadn't replied when I sent this so feel free to ignore

 

[miksan]

I knew the stick tests were notoriously inaccurate - I've watched Petco employees test water with test strips a year out of date. But I did not realize such a problem existed with the API product. You both are right. I thank you both for the heads-up regarding the API product. Any input regarding a good test product for pH, Ammonia, Nitrate, and Nitrite?

I retested the Nitrate and shook both bottles like a paint shaker mixing a new color for about 1.5 minutes - the result was between 10 and 20 ppm. However, I'll need to replace this treatment, since the 'part two' chemical is now very 'concentrated' and the true result is unknown.

FYI. Since adding an aerator to the first stage filtration chamber, the fish appear less stressed. I plan on running it all night and then putting it on a timer to run every night. I am assuming that the nitrate was kicked up quite a bit when I cleaned the Caribsea Floramax - That with the false test is a big factor. Even though my tests were good, I executed a prophylactic by adding one cap-full of Prime when I first noticed fish in stress and dying. I would have thought that would have locked-up any ammonia, nitrate, or nitrite.

 

[miksan]

PS. You can see an early setup of my new Uniquarium at http/www.amazon.com/Marineland-Capable-Aquarium-Lighting-System/dp/B00494NBEA/ref=sr_1_1?ie=UTF8&qid=1358129451&sr=8-1&keywords=marineland+reef+capable+led+aquarium+light - This is about six months prior to Marineland introducing their LED "plant" version. I used the stick medium for testing in the video.

Fish and plant density is the same today as then - sans five less fish and different plants. The 'reef ready' 10k is great for coral in a reef tank - but slowly starves plants (therefore the recent switch in lighting - I got tired of replanting every two to three weeks). Some habits are lasting: Since my early newbie days, I have been a champion in the principle of low stock - and slow and low feed.