Fluval Flex 34L - Always high phosphate, low Nitrate

[Polymate3D]

Hello everyone

So the past month I have been working on trying to get my Fluval Flex 34L ready as a coral frag tank. It has some live rock and a very thin coarse crush coral floor. Live rock rubble in the back with carbon. Thats about it filtration wise. No skimmer, no dosing (Except some Seachem Phyto Plankton). This live rock has been in a fish only tank for a long time so I believe this has bound a lot of phosphate.

During this past 4 weeks I have done 8x 30% water changes. This was due to calcium being really low (330), alkalinity being really high (14.5) and phosphate on my test kit always reading the maximum of 0.1. I tested the kit on fresh saltwater and it measured 0, so I decided to get a Salifert test kit. This is showing 0.25<0.3ppm for phosphate.

My nitrate test is API, but previously in a cycling tank read 80ppm, so I know it can measure a value, but this tank always measures 0<5ppm. I can't really tell what one as the colours are so close together.

I feed a regal damsel and tailspot blenny in there frozen mysis and Hikari S pellets, along with the Seachem Phyto Plankton.

There is algae growth and between the tailspot blenny and 3 hermit crabs they do a good job of keeping it under control.

But no matter how many water changes I do, Phosphate never gets low enough, and its a constant struggle to get nitrate to register.

So what would you reccomend to fix this? I have done GFO before and felt like a sinkhole for money than fixing the issue. I tried Cheato on a night cycle but that resulted in the same high phosphate outcome.

My head is looking at @Randy Holmes-Farley ammonia dosing stuff, and thinking maybe ammonia or nitrate dosing is the solution to this tank currently, used with the macro algae on a night cycle. Tell me what you think though?

Parameters taken before lights on:

PH = 8.0
Ammonia = 0
Nitrite = 0
Nitrate 0 or 5ppm (Hard to say)
Alkalinity = 10.2
Calcium = 460
Phosphate 0.5<1.0 (Salifert says divide by 3 for ppm) = 0.2 < 0.3

I feel like dosing Ammonia / Nitrate enough to get the right balance for the Cheatomorpha algae to uptake, along with water changes makes sense. Does that make sense?

- Paul

 

[skey44]

I think this is a relatively common issue that I’m working on too. I’m running GFO in a reactor and maintaining phosphates around 0.05ppm (old dry LR dark cured for months in brute with gfo running and several 100% wc). I’m consistently bottomed out on nitrates in a newer tank (approximately 2 months) with only 3 fish. I do feed them pretty heavily but still no nitrates. I’m not doing anything drastic bc the tank does look good with minimal algae growth, healthy fish, cuc, and the starter corals are doing well.

I do recommend getting the Hanna checker at least for nitrate… especially if you’re gonna start dosing nitrate. I just ordered brightwell neonitro and some new nitrate reagent to start this process before I try some trickier corals like goniopora and acros. The ammonia dosing sounds like a good idea but I liked the idea of neonitro being a premixed/commercial product with positive reviews. My LFS also uses the neonitro and has done ammonia dosing previously with a preference for the nitrate dosing.

How long has your tank been running? Sounds like you’re dedicated, I’m sure you’ll get there. I’m not sure I answered anything but letting you know the process I’m going through along side you.

 

[Polymate3D]

This specific aquarium has been going for about a year or bit more, but mainly sat as a quarantine tank for fish, so parameters like phosphate where not monitored.

I stopped the hobby for about 8 years where I moved out and now have a child. Before I was very hands on and wanting to understand everything I can, and this time around it is the same. Only difference is we have more information at hand!

Im still working on just water changes for now, but I believe there is a bigger picture thing we are missing here, as it seems to be that all the food options have a higher phosphate / Nitrate ratio than any of the macroalgae or corals uptake, so it is the by-product on this imbalance.

- Paul

 

[Randy Holmes-Farley]

Hello everyone

So the past month I have been working on trying to get my Fluval Flex 34L ready as a coral frag tank. It has some live rock and a very thin coarse crush coral floor. Live rock rubble in the back with carbon. Thats about it filtration wise. No skimmer, no dosing (Except some Seachem Phyto Plankton). This live rock has been in a fish only tank for a long time so I believe this has bound a lot of phosphate.

During this past 4 weeks I have done 8x 30% water changes. This was due to calcium being really low (330), alkalinity being really high (14.5) and phosphate on my test kit always reading the maximum of 0.1. I tested the kit on fresh saltwater and it measured 0, so I decided to get a Salifert test kit. This is showing 0.25<0.3ppm for phosphate.

My nitrate test is API, but previously in a cycling tank read 80ppm, so I know it can measure a value, but this tank always measures 0<5ppm. I can't really tell what one as the colours are so close together.

I feed a regal damsel and tailspot blenny in there frozen mysis and Hikari S pellets, along with the Seachem Phyto Plankton.

There is algae growth and between the tailspot blenny and 3 hermit crabs they do a good job of keeping it under control.

But no matter how many water changes I do, Phosphate never gets low enough, and its a constant struggle to get nitrate to register.

So what would you reccomend to fix this? I have done GFO before and felt like a sinkhole for money than fixing the issue. I tried Cheato on a night cycle but that resulted in the same high phosphate outcome.

My head is looking at @Randy Holmes-Farley ammonia dosing stuff, and thinking maybe ammonia or nitrate dosing is the solution to this tank currently, used with the macro algae on a night cycle. Tell me what you think though?

Parameters taken before lights on:

PH = 8.0
Ammonia = 0
Nitrite = 0
Nitrate 0 or 5ppm (Hard to say)
Alkalinity = 10.2
Calcium = 460
Phosphate 0.5<1.0 (Salifert says divide by 3 for ppm) = 0.2 < 0.3

I feel like dosing Ammonia / Nitrate enough to get the right balance for the Cheatomorpha algae to uptake, along with water changes makes sense. Does that make sense?

- Paul

Not sure how you got calcium that low, but for sure, water changes are an exceptionally expensive way to raise calcium.

Dosing ammonium or nitrate seems like a good plan to me.