 Re: Rimless 75 gallon - close loop filter
When scientists first started studying the microorganisms that live in an aquarium filter they found several that seemed to be the ones responsible for turning ammonia and nitrite into nitrate. The bacteria they found had a dormant stage, were easily bottled and had a reasonably long shelf life. Unfortunately these are the wrong bacteria. However, these are the ones that you will find in most cycle assisting products. Even if they are not specifically labeled as to what species of bacteria, they are often labeled, "Use with every water change"- Hint: These bacteria do not hang around in the filter.
Marineland started making some investigations and growing microorganisms in different ways and found the bacteria that are the real workhorses in a filter. They also found that these bacteria do not have a dormant phase, and had to be kept cool (not frozen) in transit and until used in an aquarium. These shipping and handling concerns have created problems and reports of failure when using Bio Spira: it either froze or cooked somewhere in the loop. They have been working on this problem so the material does not need to be refrigerated and will have a longer shelf life.
It is, however an excellent way to cycle a new tank: Add Bio Spira, let it circulate for a short time, then add fish. The first week might show very minor blips of ammonia or nitrite, then the cycle is finished.
I think there are at least 3 companies, maybe 4 packaging these bacteria now.
For more info have a look at Marineland's web site.
Tetra makes a product with the correct bacteria, but I think it is only available in Europe.
Fritz' Turbostart seems to also promote fast cycling, but is not labeled for content.
The scientist at Marineland that did a lot of the work developing Bio Spira might have a similar product on the market called something like 'The One and Only' You might google this with the name Tim Hovanek (I think that is the spelling)
Another way to grow these bacteria is in a fishless cycle. This is a very good way to avoid the stress and damage tot he fish caused by a fish-in cycle. You said the fish were gasping at the surface, and the ammonia was high (until you ran out of test strips). The fish were gasping because the ammonia is burning their gills, and they cannot breath. After the ammonia removing bacteria grow to a big enough population the nitrite spikes. This causes Brown Blood Disease which can also kill the fish. (Google it, too) The end result is fish that have had such stress that they may always be unthrifty, short lived, sensitive to minor problems. The damage from the ammonia in the gills may only partially heal.
Using either a fishless cycle or Bio Spira is a lot faster, and much safer for the fish. | 
I look forward to the updates
One of those that jumped out later died a few days later, maybe from head trauma. I'll be getting rid of these fish soon so make room for more plant friendly species so hopefully no more try to commit suicide. If I was keeping them in there for the long term I would invest in some kind of glass or acrylic top.
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