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Nexus units

Comments from Koi-keepers.
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1. Back in May this year, I decided to scrap my home made filteration system and purchase a Nexus 200 Eazy. I got a very good deal locally and installed it the same month. This is my experience with the nexus so far...

Installation on my pump fed system was reasonably easy and the compact nature of the filter freed up quite a bit of space.

My original filter consisted of 8 round barrels, two sets of four in series, all fed from a single pump fed vortex. The first four barrels housed filter brushes and the last four contained a mix of Flocor, alfagrog and clay beads.

In order to preserve some of the bacteria in the filters whilst the Kaldnes matured, I removed the brush stages and plumbed the nexus output to the last four barrels in the hope that it would keep Ammonia & Nitrite levels down.

Initially, Ammonia rose to 0.5ppm and Nitrite to 0.25ppm. I managed to maintain these levels for some time but by mid June, Nitrite was rising and reached 0.5-1ppm. Worried by this level (several fish were by now flushed pink) I added filter start to try to compensate and reduced feeding to once per day. This dropped the Nitrite to 0.5ppm which was not ideal but tollerable at least.

I went away on Holiday at the beggining of July and a freind looked after the filters whilst a Family member fed the Koi twice a day. By mid July when I returned from Cumbria, I found levels of 0.0ppm ammonia but 1ppm for Nitrite! At this stage I decided to remove the last four stages of the old bio filter and increase water throughput in the nexus. As I predicted, the levels remained the same but I was at least now running exclusively on the Nexus.

The old bio filters by the way were discusting. Full of waste and sediment, some of which smelled foul. No wonder the pond was never clear in the summer!

Incidently, apart from the first two weeks of operation, water clarity improved dramatically throughout this maturation process and continues to get better and better. Docs, which were a constant problem with my old filters are very low indeed with no obvious foaming on the water surface.

At the end of the third week of July, Nitrite began dropping back to 0.5ppm. Slowly over the coming days it continued to drop off.

Its now approximately 10 weeks since I installed the nexus and current reading are 0.0ppm Ammonia, 0.12ppm Nitrite. It does seem to take a while to establish a decent colony of Nitrospira in the Nexus filters hence the current Nitrite level, probably due to the moving media being a somewhat chaotic environment. I am confident however that the filter will fully cycle within the next few weeks.

Overall, I am delighted with the Nexus and find it very "Eazy" to use. It keeps the water pristine and the fish are looking better than they have ever looked before.

As long as water throughput is reasonable, not excessive, the static chamber is kept nice and clean with regular waste flushing (something that should be done on any system anyway) there is not too much kaldness and too much air being pumped through it (A common mistake I think that may well explain several end user nagging Nitrite problems) then these filters are absolutely fantastic, even in pump based ponds and I would not hesitate to recommend them.

Alan F