Fighting phosphates

[kit]

Hi Guys,

I've been lurking it's been a while since I last posted
I'm hoping someone might have some input on my fight with phosphates.

Here is the situation:
- Phosphates are at 0.3 (Hanna)
- My macroalgae (chaeto) does not grow, or grows very very slowly
- I don't get algae in the display - I clean the glass once every one to two months
- I skim wet but do not appear to have a large amount of skimmate
- Most LPS seem to grow OK, but most SPS will slowly recede over a few months and eventually die
- All my rocks are covered in coralline, and coralline grows in the sump.
- There is a small patch of Cyano that grows in the sump, I suspect it is in an area of low flow.

10% water changes are with NSW every fortnight.
I'm also dosing Randy's recipe with Alk, CA and Mg.

In recent months, even some of my long term corals have start to die off at a rapid rate but I'm unsure how to tackle it.

I have recently added a very small powerhead in the sump to increase flow in the refugium chamber, I'm uncertain if this has helped the Chaeto at all

Lighting for the refugium has either been a 15w energy saving bulb in cool daylight, and recently a 12w COB LED in cool daylight. The refugium is lit from the side as I have lids on the sump.

I'm was not running any phosphate removing media, but have just in the past two days added phosguard in a media bag (I don't have a reactor).

Here are my other water parameters:
Alk: 3.0 Meq/L (Hanna)
Ca: 460mg/L (Salifert)
Mg: 1300Mg/L (Salifert)
Nitrate: 10 ppm (Salifert)

Any help appreciated.

Thanks guys

[Gats]

How on earth do you go for 2 months without cleaning glass with those parameters? Have similar with lower phosphate and got to do it weekly!


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[kit]

I've been told I'm living the dream

I do get algae on the glass but it grows so slowly I can go that length of time without cleaning the glass.. and by that time I get some white spots on the glass which I believe is calcification something along those lines.

With little algae growth, minimal skimmate extraction and plenty of coralline you would think I don't have a phosphate problem, but the readings show otherwise; plus my sps growth was always on the slow side. Add to that the recent coral loss, it's got me digging for an answer.

[bimborocks]

First thing I would do is find another local reefer or lfs and get them to test a sample of your water to verify your tests.
If you only need to clean your glass that infrequently I would be sceptical of the nitrate and/or phosphate result, either that or you aren't running any lights.

[kit]

First thing I would do is find another local reefer or lfs and get them to test a sample of your water to verify your tests.
If you only need to clean your glass that infrequently I would be sceptical of the nitrate and/or phosphate result, either that or you aren't running any lights.

That's what I initially thought as well, but my Nitrate tests were consistent across API and Salifert - despite some people's experience with API, it seems to have worked for me.
I also recently ordered a new pack of Hanna Phosphate reagents, and can see a definite colour change (to a blue tinge) in the vial after mixing the reagent.

While I don't know the exact figures, perhaps I managed to fluke the Redfield ratio?
Having said that, my tank is almost 3 years old now, and I have never had an algae issue.

[Gats]

What's your Hannah test? 736 or 713?

Also what's the top up water source for evaporation? RODI water or tap water?

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[kit]

It's Hanna 713.
Topup is with rodi water, 0 ppm tds reading on the water.

[Gats]

I'm out then

Thought it might be metal build up or something (would retard algae and coral growth), but if phosphate is 0.3 (not a typo and 0.03) and you didn't get 2nd hand rock that's leaching something, then I don't even know why you have no algae much less corals dying. Salinity or temp shifts could do it I suppose, but assuming you're all refractor'd up and that's cool too.

Following for expert opinion on this one


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[matts20891]

Have you tested rodi water for phosphates? 0 tds doesn't necessarily indicate 0 phosphate

[Boggers89]

Have you tested rodi water for phosphates? 0 tds doesn't necessarily indicate 0 phosphate

I tested my RODI and got a reading cant remember think it was 0.05ppm for phos but 0 TDS. After talking to some people I was told that the meters struggle to read RODI and end up giving false positives because of how little amount of anything is in the water.

So my understanding from all that is unless there's another way to test RODI water for Phosphates you'll just be wasting a test packet.