Salifert PO4 Tests zero but algae still growing

[Jyetman]

I have a bucket scrubber with a weak water fall. It grows lumps of hair algae when harvested size of baseball in 1.5 weeks time. Also have thick mat of grape culurapa under waterline. My API kit shows zero so upgraded to a salifert kit thinking need more precise measurements. Still shows clear zero PO4 what is going on why can't I get a .03 PO4 for proper coral growth? Algae still grows on glass and rocks not in abundance though but does this mean I still have PO4?

 

[bertoni]

For the algae to grow, the water column must have some phosphorus in it. What corals are having trouble?

 

[Jyetman]

For the algae to grow, the water column must have some phosphorus in it. What corals are having trouble?

Blue cloves shriveled and small colorful zoos are half closed no pests been doing this for years they close short time slowly open back up. The big ugly looking zoos are doing fine so are my blastos, acan, Kenya tree, montipora plate, GSP, duncans and yellow polyps. My Tank age is nearing the 5 year mark. Started doing KALK drips several months ago to maintain ALK and Calcium using single doser slow drips for 40 second every 4 minutes. All my tests are in the proper ranges Calcium @ 440 PPM, ALK 9 DKH, MAG 1490 PPM, Salinity 1.025 Refractometer and Zero Nitrates. Removed all algae from scrubber screen a week ago to see if PO4 would increase still reads zero zoos slowly opening but look bad. Not sure what to do next?

 

[Jyetman]

This is what my green zoos look like and others very similar. They open in the morning and by mid afternoon half start to close up. Over a year ago I bought a single Armor of God polyp. It use to be the size of a nickel but closed up and five months later opened. Never got large again but grew seven others. Those seven would open and close periodically but in time reduced down to two polyps. I just don't understand what is going on other corals seem to do fine. I gave up on water dips because those closed polyps would get worse and die besides nothing came off them. If my PO4 kit reads zero could that be the problem?

 

[Sprink669]

I am having the same issue
I have tried water changes, increase flow, change filter socks every 2 days
Getting frustrated

 

[Randy Holmes-Farley]

Exporting more phosphate before the algae gets it is generally successful. A good way to accomplish that is with a binder such as GFO. Ignore what the kit says if hair algae is thriving. It takes up a lot of phosphate as it grows.

 

[dkeller_nc]

If I understand your question, you're actually trying to increase your water's nutrient levels (phosphate, perhaps nitrate) to assist your zoas.

The first thing to realize is that Salifert's test kit won't give you an accurate measure of the water's phosphate content at concentrations typically desired by reef aquarists (0.05 - 0.03 ppm). In order to quantitate such low levels with a wet chemistry test, you need a photometer-based assay; color comparison charts just won't do it.

Many reefers use the Hanna Checker photometer-based phosphate assay. There are 3 types: the HI717 (high range), the HI713 (low range) and the HI736 (phosphorus ultra low-range). In my opinion, the most useful of the 3 is the HI713 with a range of 0 - 2.5 ppm phosphate. The HI736 is also widely used by (particularly) SPS keepers, but in my opinion, the assay is somewhat unreliable.

But if all other corals in your tank are thriving/growing well, you might look to other potential causes of your zoanthid problems. One possible thought is based on your observation that they're open at the start of the day but close up mid-way through your light cycle. This might be an indication that they're getting too much light.

 

[Jyetman]

I am having the same issue
I have tried water changes, increase flow, change filter socks every 2 days
Getting frustrated

I hear your frustration this has been going on for years for me one month they all look good and BAM many months go by of closed, closing or partially opening zoos. Only happens to the smaller colorful zoos big ugly ones spread like a plague. Something is causing the problem just don't know what yet.

 

[JoelA7]

Hi dkeller -- So looking at hanna meters, I'm a little confused. You suggest a photometer, which seems to be this one:

http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=23791

But then suggest a model which is a colorimeter, this one:

http://www.bulkreefsupply.com/hanna-colorimeters.html

The latter being much much less expensive and in fact about the same cost as a salifert or elos test kit. Would it be rather more accurate or is the much more costly photometer needed to obtain reliable results for reefing?

Thanks.

 

[Randy Holmes-Farley]

You want the Hanna 736 phosphate checker for a reef aquarium, not the 713.

 

[Randy Holmes-Farley]

FWIW, I do not believe you have too little phosphate if you have a hair algae problem.

 

[Jyetman]

FWIW, I do not believe you have too little phosphate if you have a hair algae problem.

I have an algae scrubber and fear the phosphates are being solely consumed by the scrubber.

 

[Randy Holmes-Farley]

Then why is the hair algae growing well?

Normally, people can stop hair algae with low phosphate before most corals suffer.

 

[bertoni]

I'm not sure that nutrients are the problem, but you could try adding a bit more food to the tank each day, and watch for changes.

 

[Jyetman]

I'm not sure that nutrients are the problem, but you could try adding a bit more food to the tank each day, and watch for changes.

That's what I'm doing my fish are way skinny from not feeding enough. So for the past couple weeks increased feedings from 2 to 3 times and things do seem better as well as the fish. But some zoo colonies are slow at opening back up. Started wondering about my old plenum plate I left in the tank. Maybe toxic gasses are escaping from borrowing snails causing issues not sure.

 

[bertoni]

The plenum might be a problem due to burrowing, but I'd see whether feeding fixes the problem.

 

[dkeller_nc]

Hi dkeller -- So looking at hanna meters, I'm a little confused.

The latter being much much less expensive and in fact about the same cost as a salifert or elos test kit. Would it be rather more accurate or is the much more costly photometer needed to obtain reliable results for reefing?

Thanks.

Sorry, I should've been a bit more explanatory. Within the meaning of this discussion, a colorimeter and a photometer can be considered the same. Both the Hanna Checkers and the Hanna photometer do the same thing - they quantitate the amount of color from the assay with a good deal greater sensitivity and precision than you can do by comparing a test sample with a color chart.

And because we're interested in measuring very low levels of phosphate, and the chemistry of the phosphate assay doesn't produce a really intense color at these low levels, you need an electronic means of reading the test.

On this one thing, I'll disagree with Randy - I recommend people get the HI713 low-range phosphate rather than the ultra-low-range HI736 phosphorus. That recommendation has more to do with apparent inconsistency of the HI736 test reagents from Hanna than the assay chemistry itself.

But both the Hanna 713 and the 736 will be far superior to the hobbyist color-chart tests, which in my opinion are more appropriate to freshwater aquarium usage.

FYI - I do agree with Randy and others that you likely don't have an "low/absence of phosphate" issue, but in case you want the phosphate test anyway, Bulk Reef Supply has chosen the Hanna HI713 as a Black Friday door-buster for $34 instead of the normal $50. If you decide to purchase one of these, purchase a package of reagent while you're at it; the meter only comes with enough reagents for 6 tests.

 

[Randy Holmes-Farley]

On this one thing, I'll disagree with Randy - I recommend people get the HI713 low-range phosphate rather than the ultra-low-range HI736 phosphorus. That recommendation has more to do with apparent inconsistency of the HI736 test reagents from Hanna than the assay chemistry itself.

.

Fair enough. I was selecting it based on its specs, not necessarily users issues that some may have.

But for the 713, at +/- 0.04 ppm, I'm not sure it better than the best kits.

 

[JoelA7]

Thanks guys. The door buster at BRS is too good to pass up. So I'll try the 713. Can always upgrade.

 

[dkeller_nc]

Fair enough. I was selecting it based on its specs, not necessarily users issues that some may have.

But for the 713, at +/- 0.04 ppm, I'm not sure it better than the best kits.

Yeah, I wonder about their quoted precision. At least in my hands, and at the very bottom extent of the meter's range (around 0.05 ppm), I get very consistent results. That doesn't mean that they're accurate of course, just consistent. Unfortunately, I don't have access to an ion chromatography rig to verify the accuracy of the hanna checker's readings.

I thought about verifying it by preparing standards, but I don't really care about its accuracy at 1-2 ppm, and accurately preparing a 50 ppb standard is a bit problematic.