By Bob Goemans
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Bob Goemans corresponds with Fernando Chang (Panama City, Panama)

Fernando Chang (Panama City, Panama) writes...

Hello Bob,

Good day and I am going to briefly describe my tank and equipment, then ask more detailed questions than in a previous letter.

Tank capacity - 150 gallons

Measurements: 60" x 24" x 26"

Sump/refugium: About 75 gallons (divided into 3 chambers: 1st chamber: skimmer, 2nd chamber: sand and rubble with some mushrooms, 3rd chamber some small rocks where water returns to the main tank.

Pumps: Little Giant model #4 to return the water from the sump. Little Giant model 3 to run the chiller 1/3 hp. And Iwaki 100RLT to run the Super Squirt 4 ways for internal circulation.

Skimmer: AquaC EV240

Calcium Reactor: Precision Marine - not working properly at this time

Kalkwasser: Dosing with R/O water to replace the evaporated water.

Lighting: Two 175W metal halides, 10K on for 8.5 hrs

Two 110W VHO super actinic on for 13 hrs

These lights are located about 12 inches above the surface of the water.

U/V: 18W from Coral Life.

Two reactor chambers: one phosphate with ROWAphos and the other with a nitrate remover.

FISHES: Flame Angel, Fox Face, Blue Tang, Powder Blue Tang, Cardinalfish, Anthias, Royal Gramma, Hawk Fish, Yellow Tang, Hog Fish - all are healthy.

CORALS: Have assorted but not sure of correct names; leather finger coral, colt coral, mushrooms, zoanthids, toadstoll leather coral, clams (4), lettuce corals, yellow star polyps, green star polyps, hammer head coral and others.

FEEDING FISH: frozen brine shrimp, 3 to 4 times per day.

FEEDING CORALS: this is the big issue - have read some aquarists do not feed corals but others do. Unfortunately here in Panama products are quite limited, with Kent Marine corals foods mostly available. I have being using these without good results twice a week.

I also started about two weeks ago to daily dose C-Balance A/B and a magnesium product.

MAINTENANCE: I change about 30/40 gallons every 2 weeks. I purchase the new seawater from a shrimp farm that is filtered and treated with chlorine. I am not sure if this is good water, but is what I can buy in the local pet store. Before, prepare the new saltwater with R/O water and Ocean Pure salt brand.

Note, I do not have sand in my main tank, it's a bare bottom tank.

WATER PARAMETERS: Ca 440 mg/l, pH 8.0, Alkalinity 2.97/8.4, Salinity 1.026, PO4 0, Nitrite 0, Nitrate: 20, Magnesium: 30 mg/l, Ammonia 0, Temp: during the hot period about 27.6C and during night hours about 25.5C.


1. Feeding of corals: if we have to feed, which foods you recommend and how often we have to feed them?

2. Adding supplements such as the magnesium, trace elements, etc... how often?

3. All my fishes are OK.

4. As a consequence of feeding the corals I have a problem with the nitrate and hair algae. Also I have installed an chamber reactor with nitrate remover without luck. I stopped feeding the corals about two weeks ago, maybe I need to do something else.

5. I know we have to stop the skimmer for a few hours while feeding the corals, but what about the adding of supplements such as magnesium?

6. Do you have any web sources where I can find how or the correct way to adjust the Calcium reactor? Mine is not working properly but still am having a good measurement of calcium, probably because I do not have any SPS corals. I am adding the calcium via the Kalkwasser.

7. Why do my soft corals shrink? I was thinking that probably it's the Metal halides! I have placed the corals in the middle and bottom sections of the aquarium. Also have recently tried to have some SPS corals without good results, as they never opened their polyps.

8. What else do you think I need to improve my reef life?

I tried to be brief, but really need your expert help to see good results. Unfortunately there is big lack of information about reef keeping in Panama. We are trying to learn from the Internet, but do not get responses from anybody out there in Internet land. I am very happy you replied to my first message and asked for more information. Hopefully you can solve most of my problems and once again thank you very much in advance for your assistance.

Best Regards

Fernando Chang

Panama City, Panama

Bob replies...

Hi Fernando,

As to this letter, it was well written and very helpful! Interesting system, and very good equipment. Since your fish are healthy, lets not discuss them except to say I recommend not adding any more, as you have, in my opinion reached the systems capacity when it comes to animals that 'have to be fed.'

With that said, it takes me directly to your first question concerning the feeding of corals. I'm presently working with two hobbyists, one in Australia, and the other in Hong Kong that went with large bare-bottom reef tanks. The reason for this was they felt, as I do and have had good experience with in previous tanks, is that closed systems experience a never ending accumulation of detritus and when sandbeds exist, even vacuuming frequently does not guarantee a healthy sandbed in the long term.

Furthermore, we have found that detritus collections on bare bottom tanks usually form in areas were water currents take it, and those areas can easily be reached with a siphon hose and be sucked out, getting almost all out of the aquarium, something not possible when there is a bed of sand. And even more important, those collections of detritus on the bare bottom can be used to feed the very same corals that you have in your aquarium! They, as I have done, use a powerhead to stir-up these detritus collections, thereby causing much of it to enter system currents and 'feed' the polyps of many of the corals. In fact, in these and my aquariums where the bare-bottom method was used, 'very' little additional coral feeding was ever done, even with species that basically fed at night. Not only did corals benefit, overall water quality remained excellent, and water change frequencies were reduced.

As for your aquarium, the photos sent show quite a lot of live rock, and maybe the initial stirring of detritus will cause a 'snowstorm,' but recommend trying this direction to feed your corals and getting away from prepared store bought products. Suggest first surveying the detritus situation on the bottom and if excessive in some areas, siphoning off a good portion. Then, using a powerhead, point it towards the areas where accumulation exists and allow it to feed the corals. If there is an excess of detritus on any of them or the live rock, use a turkey baster or smaller powerhead to sweep it away. Currents will also carry some of this detritus to your mechanical filter, which should be cleaned after each 'so-called' feeding. Once this more natural method is utilized several times, (once weekly would suffice) the accumulation of detritus will begin to dwindle. Furthermore, when it comes to feeding corals and various other invertebrates, only non-photosynthetic species actually 'require' special attention to their nutritional needs. Those you have will do well without any direct feeding.

When it comes to water changes using water coming from a 'shrimp farm,' that concerns me. I've done consulting for some in the past and tremendous nitrate levels were always a major problem that were limiting the farms lifespan. The use of chlorine will get pathogens and other live organisms, but does nothing else. I would go back to using a quality RO 'and' DI for making the water needed for evaporation makeup and water changes.

Your water parameters seem good except for magnesium, which has probably been read inaccurately. Retest and let me know before we make changes (Reader note - it was inaccurate and was really about 1200 mg/l). If needed, Kent makes a good Magnesium additive and we'll go from there. As for C-balance, that's a two-part calcium and alkalinity buffer, and maybe once we get the calcium reactor working properly, it won't be needed.

As for adjusting the calcium reactor, for beginning almost any large aquarium, e.g., 100 gallons or larger, I've found a bubble rate of 60 per minute and a drip rate of 110 drops per minute a fairly good starting point. I also recommend testing, every other day, the 'effluents' alkalinity, and adjusting carbon dioxide bubble rate accordingly to maintain a level of alkalinity three times that desired for the aquarium, e.g., if desired aquarium alkalinity was 2.5 meq/l (7dKH), the effluent should be 7.5 meq/l (21 dKH). At the same time, test aquarium calcium and alkalinity and adjust the drip rate as needed to maintain its desired level. Once set, testing can be reduced to once every 10 days to two weeks.

As for reactor media, usually within 10 months, the difference between alkalinity and calcium levels in the aquarium may begin to widen, and adjustments to drip rate and carbon dioxide bubble rate not fixing the situation. Changing the media, even though it still 'looks' okay is highly recommended because the calcium was the first to dissolve in the media, with carbonates that are slightly harder remaining and slowly making up the majority of the entering constituents later on in the effluent. There are two media's I recommend: ARM by CaribSea, and the German KORALlith media. A third possibility is crushed coral coming from the Caribbean, as that is mostly aragonite, whereas crushed coral coming from the US mainland is mostly calcite. Do not use old pieces of dead coral as they are usually coated with calcium phosphate that may cause a severe algae problem.

When it comes to adding Kalkwasser, there are various ways to add this high pH product, and without a description of how you do it, I recommend it not be used until we discuss it further.

It's not necessary to stop the skimmer when feeding except when using 'liquid' type 'food' additives, as they might make your skimmer overflow. In fact, none of your corals really need these liquid food products. As for coral shrinkage that would depend upon their placement in your aquarium and the fact your lighting is too high above its surface. Need to know why it's so high in your next letter.

Hopefully, the above is helpful and has answered most of your questions. Lets go from here and if others in your area need help, send them my way. We aquarists are all 'brothers and sisters.'



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