water changes

[dadonoflaw]

i have a 180 gal tank with a 100 gal sump. i have been doing 30 gal water changes on a weekly basis. my question is two fold. is that too much and why have my nitrates stop coming down after falling pretty quickly when i added a 20 gal refugium. they went from 25ppm to about 15ppm and stopped.

[HowardW]

Changing about 10% weekly of the total water volume really isn't too much at all IMO depending on what you keep and the tanks bioload. Nitrates will not go lower if they're being produced as fast as they're being exported via water changes or by other means.

[Bonebrake]

30 gal. per week in your system is a good volume to continue with.

As far as the nitrates not going down further: what are the nitrates of that water you change with? Do you overfeed and/or have an excessive bioload? Do you regularly prune your refugium?

[capn_hylinur]

<a href=showthread.php?s=&postid=11254373#post11254373 target=_blank>Originally posted</a> by Bonebrake
30 gal. per week in your system is a good volume to continue with.

As far as the nitrates not going down further: what are the nitrates of that water you change with? Do you overfeed and/or have an excessive bioload? Do you regularly prune your refugium?

to add ---how much live rock do you have and how long has your tank been up?
Are you running filter mediums and or bioballs?

[dadonoflaw]

0 nitrates in source water. i dont believe my bioload is excessive as i dont fill my skimmer cup for several days. 2 tangs and a trigger are the only large fish i have and none of them are beyond 4 in. i feed 2x a day due to fairy wrasses and anthias. all of the food is consumed or nearly all as i feed with a turkey baster to make sure. i just started my refugium about 2 months ago but i have only had to prune the grape caluerpra twice. so it isnt growing really fast. i have about 400 lbs of live rock and a dsb in my tank and the fuge. my tank has been up about a year. no biological filter. no bio balls or crushed coral.

[capn_hylinur]

are you rinsing frozen food with r/o water before using--can contain alot of phosphates and nitrates from the holding tanks where they are raised.

[capn_hylinur]

you might consider gradually weaning over to cheato algae for the refugium. keep a light on 24/7 and it will grow like a weed.
As with all algae in fuges it has to be harvested regularily to remove the nitrates from the system--and you need faster flow through it then if you were using it just to raise inverts.

[dadonoflaw]

i usually rinse but i use tap water when i do it. does it matter if i rinse with tap instead of ro water? i just figured since there were no phosphates that there would be a negligeable affect on nitrates

[capn_hylinur]

over time there is the possiblity to add phosphates to your tank that can be absorbed into the substrate/live rock without changing the level in the water column. So it is probably not a good habit to get into.
as far as nitrates--honestly I don't know if tap water could be a source?

[bertoni]

The Caulerpa might do better with more light. Also, most of the food that goes into a fish comes back out, so the amount of time an animal takes to eat food is irrelevant to the overfeeding issue. Tap water can be a source of nitrate, but that's not particularly common for the level of nitrate present in the tank. I suspect overfeeding is an issue.

[dadonoflaw]

sorry i was unclear. i use a kent rodi unit and the resulting water is nitrate free. where i live water is almost undrinkable. i will be more diligent about rinsing the food and see if that helps. how can you tell if you are over feeding if the food is consumed? also i light my refugium 24/7 after some advice i received.

[dadonoflaw]

sorry i was unclear. i use a kent rodi unit and the resulting water is nitrate free. where i live water is almost undrinkable. i will be more diligent about rinsing the food and see if that helps. how can you tell if you are over feeding if the food is consumed? also i light my refugium 24/7 after some advice i received. also i have several kinds of algae. i have grape i have chaeto and this other stuff called dragons breath in my circle

[bertoni]

There's no useful objective test for overfeeding because systems all differ so much. The growth of algae in the display indicates that the pests are getting food, and the primary suspect is always fish food. The live rock might be contaminated with phosphate, though, and in some situations, algal pests can be very effective at grabbing nutrients with even minimal fish food added.

I'm not sure I'd light the refugium 24/7. That can work well if the lighting is not too intense, but a rest period can be a positive with bright lighting, for an unknown definition of "bright". How is the refugium lit? Is it a standard 20g tank?

[dadonoflaw]

its a 20gal high and i light it with a 55watt pc light. i only do 24 hours since i was told that it helps the algae not to go sexual in my tank. do you think i should give them a rest period based on this info. well the only nuisance algae i have now is hair algae and it is dieing. how would i know if it is leaching from the rocks and sand?

[capn_hylinur]

this is one of the reasons I suggested chaeto rather the caulerpa--it will not 'likely" go sexual.

as far as the light on 24/7--the only advantage of that --IMO is to build up a good amount of cheato quickly. After that you can go back to reverse lighting.
During the daytime you do not need it being photosynthetic---rather a night when there is the nocturanl shift in pH.

[dadonoflaw]

i know about that but i couldnt get the chaeto to grow in my tank. the caulerpa was the only thing that would grow at first. so i am worried about taking it out in case the chaeto wont grow. if i see that it grows i will remove the grape

[bertoni]

If the tank is doing well enough, I'd leave the refugium lighting alone. Caulerpa can be a problem, so trying a switch to Chaetomorpha might be useful.

[capn_hylinur]

<a href=showthread.php?s=&postid=11266686#post11266686 target=_blank>Originally posted</a> by bertoni
If the tank is doing well enough, I'd leave the refugium lighting alone. Caulerpa can be a problem, so trying a switch to Chaetomorpha might be useful.

what are you using for lighting for the fuge--I re- read the post but maybe I missed it?

[dadonoflaw]

i am using a 55 watt 6500k pc light strip

[capn_hylinur]

I am using a 25 watt energy saver bulb and holder from Home Depot:

http://i142.photobucket.com/albums/r107/reefescapetangster/IMG_4527.jpg

http://i142.photobucket.com/albums/r107/reefescapetangster/IMG_4522.jpg

http://i142.photobucket.com/albums/r107/reefescapetangster/IMG_4521.jpg