HOG1 working but not enough

[tasos]

I have a 100litre (25g) cube with built in back filter. I use a HOG1 about 3 years now and the tank is barebottom with old live rock.Tank is skimmerless and the filter has activated carbon every month the HOG and extra pieces of live rock . I can't lower the phosphate enough (0,05-0,2) but the nitrate levels are always zero. Most of the time hair algae thrives in the tank rock, glass and pumps, at all levels in the tank, and in the HOG too, where I get thin strings of dark green algae. I tried to feed more(4-5 pinches of flake) with no results in nitrate level, but got a bit cloudy water every time and lost all my snails.There is a happy clownfish and a brittle starfish in the tank.I tried to bring nitrate up with KNO3 but it didn't accelerate the algae growth in the HOG. Tried to clean the rock manually to give advantage to the HOG but the hair algae returned as it was. Switched off the tank lights of periods of months( no corals) and kept feeding and nitrate level climbed up to 20ppm but the HOG didn't grow more algae. When i switched the lights on in the main tank the hair algae appeared again. I tried iron, manganese, and potassium to help algae in the HOG with no significant results.Ca, Mg, KH are fairly stable. Lights on the HOG are 24/7 most of the time but algae grows slower in the center.Should I cut some hours off?

[SantaMonica]

Welcome from Greece. A photo with the red light off would help. But yes if the middle has not filled in yet, and if the bubbles are strong and go up the middle, then you can do 18 hours of light.

Also you should be cleaning often, to get what growth there is, out.

[tasos]

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[tasos]

I saw bubble rising from the sides so I cleaned the airline tubing with some vinegar.Thanks for the reply!

[SantaMonica]

The whole thing needs brushing off in your sink, under running water, each week now. Go to 24 hours of light and bubbles too.

[tasos]

OK.Thank you!I will keep you informed!

[tasos]

Hello again and happy new year!! So I went from 18 to 24 hours lighting- the air pump was 24 h anyway- and no significant growth was noted at HOG... So I followed your advice to another hobbyist to remove all sponges and mechanical filtration from the back filter.I left only some pieces of live rock and a handful of pumice stone pebbles that had created a rise in nitrate levels up to 50ppm in the first place.Also half a cup of activated carbon for clearing the coloration of the water.In just a week's time growth in HOG doubled and I started to see more sponges in one of my rocks in the DT!! I was amazed and kept feeding. Now the growth in the HOG is steady and plentiful and coralline algae started to expand in my DT !! Nitrate levels went down to 20 and phosphate seem almost zero in just a matter of weeks. There is some green algae on the glass of the DT, that it seems to me as a precursor for coralline, but no cyano, diatoms or hair algae on the rock, glass or pumps. Also snails are more active now in cleaning the tank. I will slowly increase the lighting period in DT from 6 hours to 10 and report back to you! I clean HOG only with my fingers now every 5 to 7 days and is going great! Thank you!!

[SantaMonica]

Nice! Yes any kind of mechanical filter will remove the food particles that sponges and forams need to eat continuously.

[tasos]

Hello! I hope everyone is well and clear from corona virus infection!!
As for the aquarium I had HOG 1 transferred to a 30lt (8G) aquarium(I will write about it in another post), and made an DIY HOG with double the screen surface an 6 red cree leds (driver 0,7 A) on the outside unit. Distance from the screen is double(ish) because of the bigger food trays I used.(there is a photo of the internal unit at 8 days growth in the end). It is working very well and after the initial shedding of the light for a week, it is growing algae like crazy! Nitrates were about 20-30 (salifert) before the new ats setup and now is 0-2 ppm after 1 month of use.Phosphate is 0 ppm ( salifert), as it was before changing the ATS unit.I food that hair algae (derbesia) found its way in the tank again, not dominating the surface of the rocks, but staying as a threat...It followed the growth of some types of macro algae that started growing as the HOG 01 worked enough as I described in my previous post. Snails don't it both macro and micro algae but keep in check the diatoms that also started to appear on the rock. Finally, the gracilaria I purposely added to the tank one year ago is also has grown five fold. I know if I add a sea hare to the main tank, will solve the problem for now, but I want to find the reason that a more powerful unit (ats) has lost the control over the derbesia. I suspect that it struggles due to nitrate deficiency. Light period of ats is 24h.80188019

[tasos]

I feed the same amount of food because the increasing the feed amount created foam from organics in the water and scared me of fulling the water.

[SantaMonica]

Sounds like phosphate may be coming out of the rocks:

Phosphate flow out of rocks

Many people, when they get their scrubber running for the first time, get worried when more (not less) algae starts to grow on their rocks. It seems really strange, especially when nitrate and phosphate tests have been lower than before. What is happening is that phosphate is coming out of the rocks. Remember, phosphate is invisible, so you can only see the effects of it, and it always "flows" from higher concentrations to lower concentrations (just like heat does).

Example: If your room is warm, and you put a cold object on the floor, heat from the air in the room will "flow" into the object until the object and the air are the same temperature. Example 2: If you put a hot object on the floor, heat will "flow" out of the object and go into the air in the room, again, until the air and the object are the same temperature. Now suppose you open your windows (in the winter). The warm air in your room will go out the windows, and it will get colder in the room. The object on the floor is now warmer than the air, so heat will flow out of the object and into the air, and then out the window.

Think of phosphate as the heat, and your rocks as the object, and your windows as the scrubber. As the scrubber pulls phosphate out of the water, the phosphate level in the water drops. Now, since the phosphate level in the water is lower than the phosphate level in the rocks, phosphate flows from the rocks into the water, and then from the water into the scrubber. This continues until the phosphate levels in the rocks and water are level again. And remember, you can't see this invisible flow. It's like a fast flowing, but shallow, river. And it can be much more phosphate than how much you are feeding each day.

This flow causes an interesting thing to happen. As the phosphate comes out of the rocks, it then becomes available to feed algae as soon as the phosphate reaches the surface of the rocks where there is light. So, since the surface of the rocks is rough and has light, it starts growing MORE algae there (not less) as the phosphate comes out of the rocks. This is a pretty amazing thing to see for the first time, because if you did not know what was happening you would probably think that the algae in the scrubber was leaking out and attaching to your rocks. Here are the signs of phosphate coming out of the rocks:

1. The rocks are older, and have slowly developed algae problems in the past year.

2. The scrubber is new, maybe only a few months old, and has recently started to grow a lot; possibly dark and thick.

3. Nitrate and phosphate measurements in the water are low, usually the lowest they have been in a long time.

4. Green hair algae (not brown) on the rocks has increased in certain spots, usually on corners and protrusions at the top.

5. The glass has not needed cleaning as much.


Since skimmers, filter socks, etc don't remove any nitrate and phosphate, and waterchanges and macro's in a fuge don't remove much either, most people have never seen the effects of large amounts of phosphate coming out of the rocks quickly. But sure enough, it can with a scrubber. How long does it continue? For 2 months to 6 months, depending on how much phosphate is in the rocks, how strong your scrubber(s) is, and how many other phosphate-removing filters you have (GFO, carbon dosing, etc). But one day you will see patches of white rock that were covered in green hair the day before; this is a sure sign that the algae are losing their phosphate supply from the rocks and can no longer hold on. Now it's just a matter of days before the rocks are clear.

[tasos]

Symptoms much, but timing is wrong.This situation started after 3,5 months after the rock cleared from green algae and turned purple from coraline.Having PO4 zero(ish) all these months, is a bit odd that algae started to grow now. I hope you are wright as you are more experienced!If it is not the case, would be better to turn the ats light for 18h in order to have more stable NO3 values for the algae to eat the PO4 also.The glass is catching algae more often now, usually when the screen is full like the picture...

[SantaMonica]

If the glass is growing more when the scrubber is full, then you are probably waiting too long to clean the scrubber. Usually the glass will grow after you clean a scrubber, because the filtering stops. But if you don't clean the scrubber, the filter will still stop once it cannot grow anymore. So from your photo I would say to clean every 5 to 7 days.

Diatoms on the rocks is a sign of nutrients in the water increasing, which would again happen if you waited too long to clean the scrubber.

So clean the scrubber more often, or, clean half of it every 3 days.

[tasos]

Thank you! I will try cleaning every 5 days and post the results.