Cyano breakout after every water change

[yohann976]

I change 15 gallons of water, twice a week from my 90 gallon tank. After every water change, I will see patches of cyanobacteria throughout my tank. This stuff will develope within hours.....maybe even minutes! Probably, by the time I finish this post, I'll have a few patches.

The patches usually don't get too large, maybe a inch in diameter tops. They grow for about a day or so, then they stop growing. If I wait a few extra days to change my water, it actually dies off.

My tap water has zero in terms of nitrates and nitrites. Within the tank, my nitrates are around 10ppm and my nitrites are at zero. I'm assuming that it is something in my tap water because it only forms when I change the water. What could it be?

 

[malkore]

well, cyanobacteria typically forms when your tank water is 0ppm nitrates, or there's not enough circulation.

My guess is your test kit isn't accurate and you have less nitrate than you think, and the water changes cause it to completely bottom out.

After a water change, planted tanks should be dosed back to proper Macro parameters, adn 1-2 days after that, dose micros.

 

[yohann976]

Where do I get an accurate test kit? I have a test kit by Jungle right now

 

[Purrbox]

Most people use the liquid master test kits by either Aquarium Pharmaceuticals or Hagen. These are much more accurate than the dip strips that you probably have since you are using Jungle. Even the liquid kits by these two manufactures can be inaccurate when you get to levels below 10ppm. For a kit that is accurate even at these low levels be prepared to spend a pretty penny as you would need to switch from hobbiest to professional grade kits. The LaMotte kits are the ones I've seen most recommended, and will cost you at least $50 for just the Nitrate Kit.

I would recommend trying a hobbiest grade liquid testkit and then go from there. If you're just going to buy the Nitrate kit, I wouldn't recommend Hagen as I find it very hard to read. The colors that the kit produces don't match well with the comparison chart in my opinion. If you want to get a Master Kit, then the Hagen may still be a good option as it contains the kits for Phosphates and KH which are very handy when dealing with planted tanks. In this case you might want to purchase a separate kit for Nitrate if you find Hagen's hard to read. www.BigAlsOnline.com has very good prices on these test kits.

 

[malkore]

I'd definitely get the Aquarium Pharm. master test kit...I too couldn't hardly read the Hagen nitrate kit.

 

[src]

I'd definitely get the Aquarium Pharm. master test kit...I too couldn't hardly read the Hagen nitrate kit.

In case you don't already know this, PetSmart is selling the freshwater master test kit for less than $14 online, and if you take a printout of that page with you to the store they will match it. I just did that yesterday - saving more than 50% is a nice way to end the day.

 

[malkore]

src, good tip, but be aware that it depends on the store manager on duty at the time. some are fine with matching the store's online price...but if you read the fine print on their website, it'll say they only price match physical store prices, not online stores...even their own.

but like I said, it seems to work about 50% of the time so it's worth a shot. otherwise the usual store price for the same kit is $20 (at least in Nebraska's Petsmart's)
*edit*
$20 was the price of the original AP fresh kit...when it had no NO3 kit, but included Kh and Gh tests. its entirely possible the MSRP went up, as the NO3 kit does have more reagents...and I wouldn't put it past a company to hike prices either.

 

[src]

src, good tip, but be aware that it depends on the store manager on duty at the time. some are fine with matching the store's online price...but if you read the fine print on their website, it'll say they only price match physical store prices, not online stores...even their own.

but like I said, it seems to work about 50% of the time so it's worth a shot. otherwise the usual store price for the same kit is $20 (at least in Nebraska's Petsmart's)

Good to know about the fine print - I wasn't aware of that. In my store (Richmond, VA), the kit runs about $29, so it was a major savings.

 

[Plantbrain]

If you are doing water changes weekly, there's no need to even mess with the test kits.

Here's a very simple, but profound question: did you get into the hobby to test water parameters or to grow the plants?

Simply doing a 50% weekly water change and dosing 30ppm per week in a fully planted tank will yield about a range of NO3 of 15-40ppm, which is fine for plants, no test kits needed. The most No3 ppm can ever build to is 2x the weekly total if you do a 50% weekly water change.

This provides less assumptions than a test does and allows you to dose the same way for PO4, K+, Traces, Ca, Mg, whatever you want.

This way you maintain a stable range of nutrients throughout the week.
A simple dosing calculator can tell you how many teaspoons etc you need to add

If you dosed 2x a week:

3/4 teaspoon KNO3
1/8 th teaspoon KH2PO4
15mls tropica master grow etc
GH booster 1/2 teaspoon

That would take care of most of the nutrients without ever having to spend $ on a test kit.
15 gal or 40 gal of tank water is not much difference time wise once you set up a water changer/hoses. You are going to do that anyway, may as well get some use out of it and avoid the test kit game altogether.

If you use a test kit, and plan on relying on it in any manner...........calibrate it, do not assume other's folk's advice or their own experiences with a so and so kit is going to be the same as yours.

All that's left is CO2 to tweak if you follow the advice I gave.


Regards,
Tom Barr