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This process puts ortho-phosphate back into the water, making ortho-phosphate levels rise again. The rise can bring the PO4 level higher than the recommended level very easily if this break up of phosphate based compounds occurs in more than one area. Indeed this could liberate quite a bit of PO4 into the tank's water.
If this scenario occurs in enough areas of the aquarium, enough phosphate may and will re-dissolve for micro-algae to suddenly start reappearing in the tank. Remember it does not take very much phosphate for micro-algae to grow. Levels as low as 0.03 ppm. can bring about outbreaks that then need to be eradicated.
Unfortunately for many hobbyists, their tests are not sensitive enough to detect such low levels and report, as a consequence, a zero ppm level (think of what your speedometer needle does at 10 miles per hour and you have a good analogy as to why the test is not showing phosphate. The test is just as unpredictable as the way the speedometer acts).
Solutions:
The continuous use of phosphate and silicate removing compounds will certainly help as well as these compounds will remove whatever phosphate and silicate may develop in this manner.
- Strong current in the aquarium,
- cleaning the rock and especially the crevices in those rocks,
- general maintenance and husbandry
- all work towards eliminating this situation from happening.
Silicate removing compounds prevent the reappearance of diatoms (usually called brown algae by hobbyists), whereas ortho-phosphate removing compounds prevent the appearance or reappearance of green slime and filamentous (hairy) algae.
Note that sometimes all you will see is green algae or brown algae. This does not mean that you do not have the other variety in your tank as well. You may just not be able to see them as they may be covered by other types of algae growth.
Changing the compounds frequently enough is the key to getting them to absorb any phosphates and silicates (silicic acid) that may develop in this manner in your tank.
The compounds mentioned should be changed at the slightest increase of phosphates in the tank or at the slightest appearance of tiny hairy or stringy filaments on the glass or acrylic panes of the aquarium. Most hobbyists, unfortunately, forget that these compounds do not last forever.
The load in the tank, the type of filtration used, the amount fed, the maintenance you adhere to, all contribute to either lengthening or shortening the life of these products. Test regularly and inspect your tank often. If you see any algae growth, even if it is only very minimal, change the compounds immediately.
Do not wait at the appearance of algae to change the compounds, as the level of undesirable nutrients (those that make the algae grow) increases gradually. This practice leads to more algae and a problem that is harder to deal with and will take longer to get under control.
Cleaning the rock in the tank is not complicated and can be done while it is in the tank or by removing it and doing so externally. Remember, always clean the Live Rock in saltwater, not in freshwater. If you do you will kill off your biological filter existing within the live sand (which is one of the reasons it is called Live to begin with). Below are methods I suggest for doing so:
Cleaning the Live Rock while it is in the aquarium:
Using a length of flexible hose of approximately half an inch inside diameter, create a siphon that leads to a bucket or a vat placed on the outside of the tank on the floor. Move with the hose from rock to rock and siphon off whatever detritus will come loose. Be careful not to suck animals into the hose. To greatly reduce the amount of water that comes out at the same time as all the particulate matter you are removing, pinch the hose closed when you move from one area to the next.
Siphon out whatever lies on the bottom as well. Try to siphon between, behind and underneath rocks too. This is not as easy but, with a little practice, you will be amazed at how much dirt and detritus you actually remove from the tank. Watch the bucket or vat and empty it when necessary.
Keep on siphoning until you see no more dirt, detritus, or whatever you want to call it, that can be removed. Since a good amount of water will be missing from the tank you will need to top the aquarium off. The water you use to do so should, ideally, have been prepared the day before so it has had time to age and all chemical reactions that need to take place have indeed happened.
Newly prepared saltwater added immediately to a tank creates stress due to chemical reactions between the dry salt components and the water. It takes from 18 to 24 hours for a batch of saltwater to stabilize itself. Additionally, if chlorine were present this process will eliminate it through simple aeration of the new saltwater mixture. There is no need to add dechlorinators (diluted sodium thiosulfate) to the water.
Siphoning behind and underneath the rocks is not always that easy. What I usually do is stir up the dirt that is lying there with the output of a powerhead, then I wait till it settles again and subsequently I siphon it out. Sometimes this has to be done several times before you get the majority out.
Cleaning the rock outside the aquarium
This procedure only works when the rocks can still be removed. If they have been in the tank for a long time, and if you have maintained high calcium levels, they may very well have "grown" together with calcium carbonate. If you can remove them though, here is the method to follow:
Conclusion:
- - Have two buckets or vats filled with salt water, ready
- - Have towels around
- - Place the buckets on water resistant material (e.g. a plastic sheet)
- - Take on rock at a time. Place it in the first bucket and swish it around holding it firmly in your hand. As you do this the dirt that is present on the rock will come loose and mix with the water.
- - Now rinse the live rock in the second bucket and then place it either back in the tank or in a holding vat.
- - Do this will all the live rock in your tank (or as much of it as you can).
- - Before replacing the rock in the tank itself, give it a good cleaning by siphoning out whatever detritus you can. This will greatly improve the water quality.
Micro-algae can reappear when phosphate compounds re-dissolve in the water, especially if this occurs in several areas of your aquarium at the same time. We have seen that a low pH in those areas is the cause of this phosphate and silicate build up.
To avoid this from happening you should ensure good strong current inside the tank, and clean the aquarium and the live rock in it regularly. Additionally, about every 6 months you should really give the tank a complete clean out to remove whatever precipitated phosphate compound may be present.
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