Close down scrubber ? Remove high phosphate

[Philrowles]

Hi everyone,

I have been reading some posts for some time now but I cannot seem to find any relating to a problem I have.
I have been running my scrubber for some time now, nitrates went from very high to un-detectable at a good rate of a few months. Only problem is my phosphate has remained at about 0.10 ppm. I have tried rowaphos in various amount in a reactor. No matter how much I have used from 100ml to 500ml amounts my phosphate hasn't moved.

I have had my test kit double checked with my LFS to be safe.

I am thinking of either shutting down scrubber and running rowa for couple of weeks see if that makes any difference.

Or regular cleaning of screen say every 4 days or so whilst running rowa, see if that makes any difference.

Anyone else had similar experiences or tried the same.

Thanks for any help

[rleahaines]

I had a similar problem. Harvesting the algae should be done normally - keep in mind the algae growing there uses the Nitrate and Phosphate.

What I did to reduce the phosphate was to look at what I was putting in the tank closely and the capacity of the scrubber.

I found that the brand of food I was using had higher phosphate levels than other brands so I changed.

Even though the scrubber was sized to the amount I was feeding, I found that I needed to increase the amount of scrubber capacity by increasing flow and area.

Depending on how old your system is, if you have a substrate, how much live rock you have in it and so on, what is in your system may also be contributing to the amount of phosphate in your water. As the scrubber uses up what you put in every day you use up the nitrate. Phosphate - organic and inorganic - seems to somehow end up in your rocks and substrate if it is not used up by the scrubber.

This comes out eventually. To use it up faster you can add GFO and rowa to the system. This will clean up the immediate issue, but when you stop your phosphate will go up again until you finally use up most of what is in your rocks etc.

Same thing will happen if you do a lot of water changes. You can reduce the phosphate, but it will go up again.

My recommendations.

Keep the scrubber going - perhaps add additional capacity with more hours of lighting, more flow, and more surface area.

See if you can reduce the amount you feed daily. Everyone over feeds.

Use GFO and/or rowos.

And perhaps a more radical suggestion. Just let things settle down running the scrubber - if your nitrates are under control, and you are not getting other issues in your tank like an algae bloom and your livestock seems happy, let it go.

[SantaMonica]

Welcome from UK.

Phosphate is probably come out of your rocks, since rocks store it. Give it time.

[Philrowles]

Thank you SM for the advice, my system was about 18 months old when I come across this forum, at that time I had sky high nitrates and phos was obviously high although was not testing then due to lack of understanding and experience. I have been running the scrubber for quite a long time now. I have got terrible diatoms / browning on sand and rocks. The screen started off black smelly sludge at first then slowly turned lighter and more yellow in colour. I have reduced light hours per day. What I found was no matter how much or little rowaphos I use the phos just didn't move on the scale, even when taking the phos reactor off line the phos didn't change in my system. Is it possible that when using rowaphos it can pull phosphate out of the scrubber ?

[SantaMonica]

Yes rowaphos can slow a scrubber down. But if you can measure P, then there is still plenty in the water.