I recently posted about my major fish deaths in my 55 gal planted aquarium after an apparent CO2 regulator malfunction. As per advice I received here I invested in a quality drop checker from Green Leaf Aquariums. I also got a new bubble counter with a thicker non-toxic fluid, purchased a new glass diffuser, changed the airline tubing and adjusted my Azoo regulator to 30 psi. Both glass bowls in the drop checker now have the same desired green color so I believe that my CO2 injection issue has been solved and my plants are getting bigger and look better.
As far as remaining fish, my 4 emerald and 1 albino corys are great as wel las my 6 H. rasporas and several Otos. My 2 plattys have apparently mated since I now have 4 babies swimming about.

I decided to re-stock the tank with only small colorful community fish and recently added 5 hardy zebra danios as a start. As of today only one remains and I also found a dead Oto.
All this after starting to use dry ferts on EI regiment and 50% water change on Sundays. I am kind of stumped at this point?

Any suggestions? Thanks to all of you.

EI is tricky. Do you have testing equipment for what you're dosing? Here's my experience with EI:

The dosing instructions that I've read are very subjective. Plants consume vastly different levels of nutrients based on the type of plant, size of plant, health of plant, etc. Dosing the recommended levels of phosphates for a 20-50 gallon tank in my 29, I was overdosing the %#$^# out of the tank and ended up accidentally killing off most of my RCS. At the same time, dosing the max for nitrates, I was getting readings of zero nitrates halfway through the week and had to up my dosage. Iron never seems to stay long in my tank, either.

EI is also very subjective based on what type of water you're adding to the tank. If your tap water is hard water, for example, you won't want to dose Grumpy's GH Booster. Part of my phosphate problem was that the water out of my tap measured a solid 2 ppm phosphates, and I was adding more, while at the same time I wasn't adding enough nitrate or iron for my plants to fully utilize the excess phosphates.

So, in conclusion, test the #%$^$ out of your tank for a solid week or three while you dose, and adjust according to how much your plants consume throughout the week, and what you're putting in from your tap.

Not sure if that's the cause of your fish's deaths (which I'm sorry for), but it very well could be if it's an excess of phosphates or nitrates.

Just my thoughts...

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Officially fishless until after the move....tune in later for details!

Dosing should not have killed your fish though. Have you tested for nitrates or anything else to eliminate other causes?

Thanks for your advice. I guess that I am going to have to obtain some test kits for nitrates and phosphate, etc.
I am using the standard EI method of dosing Macros NPK at the rate of 1/2 tsp of N and 1/8 tsp of P and K 3 times a week and 1/8 tsp of Micros 3 times a week with a 50% water change on the 7th day.
I will test and adjust as needed.
Thanks again

I was also going to say test Nitrates after you said you started dry ferts.... one of the reasons I'm a bit hesitant to start them..... hope you figure it out! Sorry for your losses!

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20g Heavily Planted http://www.aquariumforum.com/gallery...00&ppuser=8981
36g Bow Front Heavily Planted http://www.aquariumforum.com/gallery...00&ppuser=8981

Thanks Holly and all members who provided advice.
Today I conducted both Ammonia and ph test at home and there was 0 ppm ammonia and my ph was approximately 6.2 - 6.4.

Since the fish that expired were recently purchased at my local Petco (due to lack of a real aquarium store here) and they advertise free water testing, I brought them a fair amount of my recently changed (50%) tank water.
They did a multi-test strip reading and even though the ph tested about the same 6.2 - 6.4 all of the other water parameters were fine and they stated that perhaps I received an unhealthy batch of fish.

They happily provided 5 new fish ( I chose different danios) and before releasing them I dosed the tank with Seachem Neutralizer to address the low ph issue.

I have decided to use iron and trace tabs placed directly into the substrate for the rooted plants and dose dry fertilizers very lightly and infrequently for the near future.

Again thanks to all f you.