Even N03 of 20 is not really high, unless you have SPS corals. Fish certainly don't mind. But you should get a better test kit.

What do you use for P04? Many of the cheaper ones do not measure accurately at the low end. Salifert or a Hanna LR checker work well. I used to think I had no phosphates or very low until I got a Hanna Phosphate checker.

Having said all that, one of my tanks used to have high nitrates (40+ consistently) and high phosphates (over 1.0), but I still did not have a cyano problem because of my MB7 dosing. It adds beneficial bacteria to your system which out competes cyano.

You'd be better off changing 10g of water every 2 weeks.

Thanks for all the input. I will be getting a new test set next week. I need a more accurate mag, all and calcium test anyways. Hagen six. I will deff be looking into that mb7. And really? You think it would be more beneficial to my tank to do 10 every two weeks instead? why is that?

You get a bigger vol turnover in your tank with 10 g every 2 weeks instead of 5 every week. Do the math.

Or think of it this way. If you changed 50% of your tank every week, or 100% every 2 weeks, which will provide a more complete turnover of your water? Of course that is not practical or recommended, but just wanted to use that example to help make the point.

Makes perfect sense. I will start doing that next time. Thanks for the advise!

could it be red slime?

Yup, red slime and cyano are one and the same

Looking into it further, I think I may be running my lights way to long as well. I believe that could be an additional reason as to why I have cyano bacteria. How many hours a day do you guys run your lights?

Depends on what type of lights and intensity through the day. I run LED's in "Natural Mode" for 12 hours. But they ramp up slowly to a peak at "noon" and then back down through the afternoon and evening. I also have mine set for deeper water, so that reduces parts of the spectrum.

What are yours?

Just to comment a bit on this. The progression of the breakdown of nutrients in our tank systems starts with ammonia after they begin to de-compose. Beneficial bacteria in our tanks feed on this ammonia, process it and turn it into nitrite. More bacteria then grows and feeds on this nitrite and turns it into nitrate. If you have a deep sand bed or other area that is very low in oxygen, or an anaerobic area, there are further bacteria that will process this nitrate and turn it into nitrogen. But if there is no deep sand bed or anaerobic area, the nitrates sit there until you get rid of them with water changes.

If you have a sudden spike in nitrates without a reading of nitrites or ammonia in the days previous, the only answer I can think of is an error in testing of either of the 3. If you are in fact testing every day and diligent in those tests, it would seem unlikely (but not impossible) that both the ammonia test and nitrite tests got fouled and you caught it in the nitrate test. But if the first 2 tests were accurate, I'd suspect the nitrate test could be inaccurate. This is where good quality tests and a clean, conscientious routine of testing is invaluable.

You may not have enough flow near your sand bed either, allowing detritus to accumulate there. I have Orange Spot Sleeper Gobies in my tanks, which constantly sift the sand and keep it stirred up. I think that helps, too.