Denitrator Question

[OhNeil1969]

I've been doing research on keeping discus and come to understand that they don't handle high levels of nitrates. My tap water at times will come out with 10 ppm nitrates. From what i have read, that's too high for discus. As a result I've been looking into a denitrator. Most of the info I've found relates to saltwater tanks. I have found this site for a commercially made denitrator: Aquarium DeNitrator, Denitrators, Poseidon X1, X2, X3 Denitrator systems ; Nitrate Removal Filter . Does anyone have any experience using a denitrator in a freshwater tank? If I understand what they do, does that mean that I won't need to do water changes in an established tank? What are the risks/drawbacks associated with using a denitrator? I also found this site about making your own denitrator: DIY Coil Denitrator Plans - DIY Coil Denitrator Plans . Again, this info seems to be directed at saltwater enthusiasts. Really would love to here from someone that has had actual experience with using some version of a denitrator in a freshwater tank. Right now I'm thinking of adding one to my 60 gallon community tank as a test prior to jumping into keeping discus.

 

[Fishguy2727]

Discus, like any fish, need high quality water. One of the things that lowers water quality is nitrate, but other things are even more important (growth inhibiting hormones, dissolved organic compounds, etc.). These are not removed be a denitrator. The reason we focus so much on nitrate is because that is what has hobbyist grade test kits available and in general nitrate concentration correlates well with these other chemicals (except in a planted tank where nitrate is removed).

Even if the nitrate concentration is undetectable you still need to do water changes. Those other chemicals will keep building up and need to be removed. In addition, water changes also bring in good things (certain minerals, KH, etc.).

High quality food and water will allow your discus to thrive. I feed New Life Spectrum exclusively and had discus breeding in the sales tanks at the shop I was running. I do weekly water changes of 80%. With discus you could do at least 50% and they should do well. If you get them and stick with the water you have and have some issues then we can look into other options. One would be diluting your tap with RO or distilled water. This will dilute hardness, nitrate, and anything else in the water.

 

[OhNeil1969]

Thanks for the info. I understand what you are saying about replenishing minerals. KH, etc with water changes and am perfectly willing to perform needed water changes to ensure that the discus get everything they need. The confusion I continue to have is what is considered an acceptable nitrate reading for discus. Right now I have 2 tanks that I see around 30 ppm nitrates after a week. The info I've found concerning discus seems to indicate that those levels would be too high. If I understand what you are saying, those people that say 30 ppm of nitrates is too high for discus are using their nitrate levels as an indicator of other issues and nitrates in and of themselves are not the culprit for poor discus health. If that's the case what are the other water quality issues that correlate to nitrate levels that are dangerous to discus.

Also, with respect to distilled water, my understanding is that because it lacks the buffers that lead to high GH readings, that using it especially in a mixture could lead to pH swings. From what I've read and learned, pH swings are more dangerous than having a fish acclimate to "foreign" pH levels. Please note that I'm sincere in my questions and that I'm looking to gain good knowledge prior to keeping what I consider to be a beautiful breed of fish. Any and all info will be greatly appreciated. Finally, I willingly acknowledge that I could be wrong in some of my assumptions. So don't worry about offending me if you feel the need to correct any errors on my part.

 

[Fishguy2727]

GH has nothing to do with pH, that is KH. KH controls pH. Nitrate generally correlates with anything that builds up over time, like growth inhibiting hormones (which discus do give off), dissolved organic compounds (build up in every tank), and others. Lower nitrate is definitely better, but I would say anything like 'up to 10ppm is fine, 15 or 20ppm is bad'. Lower is better.

If you start using half tap half distilled greadually you should not create any major pH change, if that is the method you choose. I would suggest not worrying about the exact nitrate yet. What it the nitrate concentration of your tap water?