Water Flow And Nitrate Issue

[matt19849]

Hi,

I’m hoping someone can help me out - I’m struggling with a few things on our aquarium at the moment, water flow and high nitrates.

We had this tank custom made but when it turned up they had changed the design of the sump from our original designs and installed all the piping in a way I wouldn’t have thought was best practice! I’ve had one issue solved on this forum with the weir so hopefully I can get some help on the this

The tank size is 1568mm (L) x 685mm (H) x 456mm (W) and sump is 760mm (L) x 457mm (H) x 370mm (W)

Our nitrates are currently coming out at 40 on an API test kit and 50 on a Red Sea test kit. No matter what we do they don’t change. It’s a 640litre tank and we’ve been doing 140litre changes a week for the last 3 weeks but they haven’t moved. We are making our own RO water which has tested fine.

Stock we only have 3 pearl scale butterflies, 2 Bangais, 7 chromis and a few hermits. There is also a sand sifter star fish and sand dollar in there with a couple of snails.

I’m noticing the weir doesn’t really suck the water through the slots - we have slots at the top of the weir and bottom, stuff does go through them just casually - if something floats past it, it won’t get sucked in. Our return pump is currently running at around 6000lph.

I’ve noticed the outlets they installed aren’t pushing the water around much - they have put 3 locline outlets on a PVC pipe shown in this pic:

Because the water flow was doing much I’ve added a powerhead to the top right corner blowing towards the weir in the back left of the tank.

In the sump the first compartment has a filter sock and some live rock, the second has the skimmer and live rock, the third has some sachem matrix and final is the return pump.

We also have a light algae reactor on the side with Cheato algae in it which I’m replacing with some pellets to help with the nitrate and we have a UV filter.

My questions are - how would I get the best water flow in the tank to make sure things are sucked up into the sump and don’t settle and is this sump the best layout, should I consider doing something else to get better filtration. I have a feeling the sump isn’t really big enough for the size of the tank but it’s all we could fit

Our main challenge is keeping the tank looking clean with no equipment on show:


Thanks for any help - sorry for the long post too!

 

[doug_amanda]

It takes a lot longer for the nitrate eating bacteria colonies to establish than the ammonia and nitrite munching bacteria so that might be one reason,
Turning your return pump up, if it will, will raise the water level in the tank and force more water over/through the weir and down into the sump, that may help but I think the main issue is water flow in the tank, three outlets on a 600lph return pump isn't enough and the flow they create will be very linear leaving lots of dead areas where crud and uneaten food can accumulate. I would get a decent powerhead or pair of powerheads to try and randomise and increase the flow around the tank to pick up any crud and keep it suspended in the water until it goes through the weir into the filter sock. The fish will like it better too.

 

[matt19849]

Perfect, i've just picked up a TMC Reef-Tide 6000 power head today which is now up and running, i'll consider adding another if this one performs OK.
I've turned the return pump up to about 6500lph now, i'll gradually turn it up but want to keep an eye on the plumping to make sure the extra pressure doesn't cause any leaks

 

[steve861uk]

From your initial post I'd say that the return pump was not big enough/turned up enough to get the water flowing through your system, but it looks like you've made steps to remedy this

 

[matt19849]

I have, adding the extra powerhead has made quite a difference too. One thing I did forget to mention was the substrate is silica sand, this was used because originally the tank wasn't gone to be marine! I think this could be some of the issue too so i'm going to start swapping that out.
Would it be best to do it half a tank at a time over a few weeks?

 

[steve861uk]

I have, adding the extra powerhead has made quite a difference too. One thing I did forget to mention was the substrate is silica sand, this was used because originally the tank wasn't gone to be marine! I think this could be some of the issue too so i'm going to start swapping that out.
Would it be best to do it half a tank at a time over a few weeks?

Silicates will produce diatoms galore and are not good for marine tanks, so best to sort that one out

A lot of people on here dose NoPox to keep nitrates in check, takes a while to work but work it does Is basically a form of carbon dosing.

 

[matt19849]

I've been dosing something similar recently from TMC called Elimi-NP. I didn't think it was doing anything but starting yesterday our skimmer has gone nuts and seems to be getting loads out so it looks like it could be kicking in now finally
I'm gone to start on changing the sand over today

 

[cuprajake]

the silica sand will stink when it comes out, do it in quarters if its been in a while, suck it out, dont add fresh sand till its all gone, and have some atm colony or outbreak on had just in case you have a spike

 

[Mike and Clare]

Just to add my opinion.
Whilst upping the return flow to the tank is a good idea, always remember there's a limit to how much will go down the overflow. You don't want to cause a flood.
The TMC power head is a nice unit, but consider adding an eco tech vortech unit. These have a more open flow than alot of units and can aid in limiting dead spots. Also the programmable (via pc) option lets you run various flow rates through the day. I can personally recommend these, having run one for a few years.
And yes, remove the silica sand if practically possible.
Just another thought, is it possible to remove the weir fronts to file them for a larger opening?
Mike

 

[cuprajake]

was never a fan of vortechs, tried them twice, went back to jecods,

if you want good flow the gyres are just about the best for moving water,

 

[Mike and Clare]

was never a fan of vortechs, tried them twice, went back to jecods,

if you want good flow the gyres are just about the best for moving water,

Different units suit different tank setups. Mines a bit odd as it has 2 sides and a large bow front, corner tank style. I struggled to find a suitable circulation unit to cope, but the vortech works well.
Unless your very friendly with your local store, being able to test units is hard, if not impossible. Relying on others opinions is the best shot, and I must agree about the gyre system. YouTube videos are also a great help.
Mike

 

[matt19849]

Thanks for all the replies, because of the style of the tank and the fact we wanted all equipment hidden I needed to find a powerhead that was small enough to hide behind the door level but still powerful. So far it's been working a treat for us.
I can file the weir fronts a little - will that help in dragging more in that way?

I've made a start with removing the Silica, it wasn't easy but i've removed 1 third so far so i'll wait a while for that to become alive before removing anymore. Is ATM Colony worth using anyway?

 

[cuprajake]

i took all the teeth out of my wier and run it smooth, gets better flow,

both the vortech i tried were really noisy tbh

 

[cuprajake]

i just syphoned it out with a water change, as i went along, colony is nitafying bacteria, it may be out break you would need,

have a quick look or ask the uk atm rep on facebook, super quick at getting back to you

 

[doug_amanda]

https://reefbuilders.com/2017/10/04/add-variable-flow-to-your-tank-with-the-rfg-nozzle/
Just seen these, they look like a better alternative to the standard duck bill fitting on loc-line returns for randomising the flow from them.

 

[matt19849]

Nice, i've never heard of those RFG nozzle things, I might give them a go though - thanks for that one. I'll have a quick chat on Facebook to the ATM guys and see what they reckon would be best

 

[Waddie01]

Hi all new to the forum but been at marines for longer than I can remember .
First thing I will ask is how long is the weir comb. Then how big are the stand pipes inside the weir box (1 inch 1.5 inch etc)
The longer the weir comb the more flow it will take to cause a noticeable vacuum and the shorter the comb the less water it will take before it over flows. Also the size of the pipes inside the weir will determin how much flow it will cope with. You will not get enough flow through your tank with return pump only. as above sensible size wave makers is a must.
When setting the wavemakers and the water movement from your return pump be away that none of these should be facing your rock as this will just blow any debris or food straight into your rocks and in turn will add to your nitrates. If its a newly set up tank i would syphon out the sand when doing your water changes all in one go. If its been running some time do it a little at a time. The fast you get it out the better.