much of this post I did on fighting algae by reducing phosphates and nitrates is appropriate here so I will cut and paste it
It adds to the excellent advice by the other posters on here
Capn's collection of shock and awe against algae
Most of the time algae is the symptom of the problem, not the problem itself.
Algae needs three things for the process of photosythesis to occur--carbon dioxide, light and food. If we could completely remove one of these elements it would not be able to survive.
Unfortunately in our reef tanks it is difficult to remove light and carbon dioxide completely but we can sereverly limit its food, mainly nitrates and phosphates.
If you have an algae problem then it should be approached in a way that limits the nitrates and phosphates in your water column
This is a combination of steps and practises rather then one magic bullet that will kill off all the algae in your tank.
Here is a list of practises that have been mentioned through a great number of posts that I have been proactive in and hopefully if they are together they might help
1. Feeding techniques----always feed less at one time but feed more often if the species of fish requires it. My fish always look hungry and so does my dog--they learn how to scam us humans very quickly.
Rinse off frozen prepared foods like brine shrimp and mysis shrimp. Quite often they contain phosphates and nitrates from die off in their holding tanks.
2. Flow rates and directions of flow can make a big difference
A rate that is quoted here quite often is that you should have between 20-40 times your tank volume in gph if your tank is mostly lps and even greater if mainly sps corals. There are still some expections with lps corals--you need to be on top of the husbandry requirements for each coral you have and place them accordingly.
Organic laden water slowly rises from the bottom of the tank to the top where it is skimmed off by various methods such as an overflow. Skimmed water is usually sent back to lower levels of the tank from the skimmer or sump via various ways such as loc lines.
In practical words this means that in the tank your flow should be directed to always enhance the above natural flow in the tank.
It should for a circle or semi circle and be pushed down, across the substrate up to the surface--across the surface--churning it up and towards the overflow
3.flow rates in the sump
The perfered answer for this question is between 5-10 times the total volume of your water column.
More importantly it should match the flow rate of your skimmer.
Otherwise unskimmed organic laden water is returned to the lower levels of the tank where it has to slowly make its way to the top like I desribed in the above flow senerio. This gives algae a second chance to have another lunch
This is also where flow rates and directions in the tank also help in this particular situation by getting the water back up to the top and out the overflow faster again.
Flow rates both in the sump and the tank are very important in the filtering process
4.Method of cleaning or tank maintenance
water changes---Randy has written in one of his articles that the ideal water change to remove nitrates is 30 per cent once of month
http://reefkeeping.com/issues/2005-10/rhf/index.php
other reefers have stated that immediate or every two week 20 percent water changes will reduce phosphates and ammonia quickly.
cleaning the rockwork and substrate--once a week take a turkey baster and lightly baste the rock and substrate with it. this will get dissolved organics, phosphates and nitrates back into the water column where they can be filtered off instead of collecting and adding to the algae smorgasboard. Once again flow is very important in this also.
change your protein skimmer cup every other day
if running a filter sock change it everyother day---soak it in bleach and run it through a wash cycle with no soap. Let them dry in the air and the clorine will evaporate
5. tweaking equipment. Try not to run bioballs in filters. Replace them and all filter media with nothing!
The best use of a canister filter is to run straight carbon in it.
take skimmer pumps apart once a month and clean out the air venturis--make sure you have lots of air being combined to give a good foam column. This helps reduce organics but it also helps displace carbon dioxide with oxygen and keep your pH stable.
Once you have your levels of phosphates and nitrates in check then you may want to consider
1. running carbon and phospban in phosban reactors. the advantage to these is the water is forced through the entire media and can't take the easy way around the outside as when the media is put in a bag. Carbon can adsorb some phosphates and nitrates and the carbon is used by active bacteria in the tank
2. setting up a refugium with chaeto algae. You will need a good size refugium 20-30 gals and about 2-3 months of intensive cheato grow for it to make a noticeble difference on phosphates and nitrates. and the other advantage of a refugium is you get a larger and more variety of copopods, other inverts and good bacteria for the water column
3. finding critters that eat algae. I leave this till the last because it is a problematic solution to algae. the critters don't always do what they are suppose to do. Putting some inverts in to eat a particular algae is great at the start but what do they feed on after they have eaten their specific food source.
4. another method that is cropping up alot more now is the use of magnesium. Magnesium should be at 1300ppm in a reef tank to support a level over 400ppm of calcium. some reefers have reported great success with cranking the level of magnesium to 1600 pppm for two weeks. the aglae dies off and none have reported any death to corals, inverts or fish.
i ask a question about water change shedules and not all but most very experienced reefers found less changes more benificial, i change 40 ltrs a week and have a 350 ltr tank, so about 12% ish, however some of the guys did only 5% a fortnight or monthly, some only did a 30% 2-3 times a year, just thought id mention this
