Hannah phosphorus checker advice

[ksicard]

I just opened up my new Hannah phosphorus checker, the one that reads ppb and not ppm. I just did 3 tests and my results were 0ppb, 2ppb, 0ppb. I highly doubt that my phosphate levels are as low as the checker indicates so I think I'm doing something wrong. Here's how I tested. Filled curvettes to the 10ml line and wiped them down with a cloth from my eye glasses (nice cloth not a rag or anything), I pressed the button to get it to read c1 and then after making sure those no fingerprints on the curvette I placed it in the checker and hit the button again. Once it read c2 I pulled it out and added the reagent and mixed till it was all dissolved and took extra care to get as much reagent in the curvette as possible. Wiped the curvette down again and placed in back in the checker and held the button till the timer showed and counted down from 3 minutes.

I really doubt my levels are as low as the checker indicates since the highest reading 2ppb is 0.006132ppm once converted. So is there something I'm doing wrong?

 

[tkeracer619]

Sounds good to me. Do you have a lot of algae that grows like crazy?

 

[ksicard]

No algae problems what so ever. I clean my glass once a week or every 4 days if I feel up to it. Maybe my po4 levels are that low if I'm testing correctly, I'll re test tomorrow to confirm. Let me know if you think of anything else that might be the issue. I do have an oversized skimmer (rated for 300g on a 75g DT), I do weekly 25% WC and 4 days ago I took my GFO/carbon offline and hooked up my bio pellet reactor with 1/2 recommended dosage. I don't think the bio pellets work that fast so I doubt that's it, I just thought po4 would raise quickly once GFO is taken offline.

 

[tkeracer619]

If the tank is void of a lot of phosphate then the rock can bind up a bunch of it before it will register. Sounds to me like you are already on top of it.

 

[ksicard]

Yeah I have a heavily stocked tank that is a sps dominant tank so I'm trying to make sure to stay on top of filtration. No3 is at 10ppm so that's why I hooked up bio pellets so hopefully I can get it down in the 1-5ppm range. I've never had an issue with phosphates and maybe they have always been super low with the GFO on top of it. I'll test again over the next week after some frozen food feedings and see if I get some more believable readings. Thanks again for the advice. And could you explain what you mean by the phosphate binding to the rock? I'm not sure if that's a good or a bad thing.

 

[tkeracer619]

Its both good and bad. Calcium Carbonate can bind PO4. Simply put it absorbs it and will leach the PO4 out over time if the amount in the water becomes low.

This is often a cause of new tank syndrome where people think everything is perfect for the first year then all of a sudden tons of algae so you go get a test kit for PO4 for the first time only to realize the tank has lots of it. You add GFO, the levels drop, but within 24h its back up to the same level since the PO4 has leached out of the rock.

Once you get loaded with phosphates it takes a lot of effort to get rid of it.

Nitrates at 10 and phos at zero? Hows the skimmer functioning? Do you get good skimmate?

 

[ksicard]

Thanks for the explanation, and the skimmer functions great I just feed heavily and have a pretty heavily stocked tank. I skim on the wetter side and I always get a good bit collected that's smelly! And good news for whatever reason I tested again this AM and I got much more believable readings, 20ppb otherwise 0.06ppm po4. Now these readings I can believe, I guess I may have not been doing something correctly yesterday when I first tried the meter. I'm pretty happy now that I wont have to guess my po4 levels now that I don't have to compare shades of the same color to get my reading. Seems like I don't have the po4 binding issue which is also good news, I appreciate the advice again thank you.